Concise answer
Each of the aforementioned actions could potentially cure his illness independently or by combining with the other two. However, the best course is to accompany all our actions—among which are medical and supernatural treatments—with supplication (which entails establishing a relationship with Allah (awj) and making a direct request from him). The reason for this is that the efficacy of a doctor’s treatment or a given medicine or, for that matter, the intercession of Imam Husayn b. ‘Ali (ع) and the dust from near his grave, is intrinsically tied to the will of Allah (awj) himself.
It is also important to keep in mind that the intercession of the Prophet (ص) and his family (ع) and supplications are not solutions limited to circumstances where one’s hope in natural means is lost. At the same time, making use of intercession and supplications does not imply that one should neglect natural solutions altogether because the divine plan for this world is that things occur as per their natural causes. Therefore, one can make use of all three aforementioned treatments. That is to say, along with supplicating to Allah (awj) and seeking the blessings of Imam Husayn b. ‘Ali (ع), one should refer to a doctor and seek medical treatment so that Allah (awj) accepts the Imam’s (ع) intercession, and thereby allows the medical treatment to confer its desired effect.
In short, under no circumstances should one lose hope in the favour of Allah (awj) and the intercession of the Prophet’s family. Similarly, by no means should one cease to take advantage of the natural means at his disposal.
Detailed Answer
Medical treatment, the intercession of saints (especially by means of the dust from near Imam Husayn b. ‘Ali’s (ع) grave), and supplicating to Allah (awj), are all means of treating the sick, so long as the person’s time of death has not arrived.
Just as it is possible for each of these three treatments to act independently by the will of Allah (awj), thereby sufficing us of the remaining two, it is also possible that all three cures combine in order to cure the sick. In particular, supplication could cause the Imam’s (ع) intercession to be accepted so that the dust from near his grave confers its healing effects. This in turn could cause the medical treatment to have its optimal effects so that the person progresses swiftly towards well-being.
However, it should be noted that the efficacy of medical treatments, and even the intercession of the Imam (ع) and the dust from his grave, is intrinsically tied to the will of Allah (awj). Therefore, as a precondition to these other treatments, supplication to Allah (awj) holds a special place. Supplication establishes a direct connection with Allah (awj) and reaffirms our belief that nothing other than him can act independently (this is known as “Allah’s unity in action” or “al-tawhid fil af’al). It is for this reason that we have been strongly advised to begin every action—including seeking the intercession of saints—by supplicating to Allah (awj) for His aid, special favour, and His acceptance of their intercession. Such advice is especially well-spoken considering the difficulties entailed in finding a skilled doctor, diagnosing an illness accurately, prescribing effective medicines, followed by a strenuous recovery—all of which make seeking Allah’s (awj) aid a vital necessity.
An additional difficulty in seeking a miraculous cure through the dust of Imam Husayn b. ‘Ali (ع), is that the efficacy of this cure requires the following prerequisites, the observance of which is difficult in this day and age:
1. The dust must be from within the sanctuary[1] of Imam Husayn b. ‘Ali (ع) and must be reddish in colour.
2. Once removed from the haram complex, the dust must be wrapped in a cloth so as not to be touched by those jinn who hold an enmity toward the Shi’a and lay in wait for an opportunity to touch the dust thereby neutering its miraculous effects.
3. Only a minute amount of the dust must be used.
4. It must be used with a pure intention without an inkling of doubt in its power to heal.
5. It must be accompanied by supplications to Allah (awj) for the acceptance of the intercession of Imam Husayn b. ‘Ali (ع).[2]
However, not to make things seem hopeless, seeking the intercession of Imam Husayn b. ‘Ali (ع), the rest of the Prophet’s family, or other saints, and seeking the blessings of the dust from each of their respective graves, when accompanied by a pure intention, is not without its effects, as testified to by numerous people’s experiences. It should be noted that for prayers to be answered and for the intercession of saints to be accepted by the will of Allah (awj), the following conditions must be fulfilled:
1. The suppliant must be sincere and focused and should accompany his supplication with salutations and prayers (salawat) for the Prophet and his family (ع) along with heartfelt repentance for past sins.
2. He must have performed all obligatory acts of worship and must have paid all mandatory Islamic taxes (khums and zakat).
3. He must not hold any belligerence to the way of life (sunnah) of the Prophet and his household (ع).
4. He must act according to the teachings of the Qur`an.
5. He must be thankful to Allah (awj) under all circumstances.
6. He must actively fulfil his duty to enjoin the good and forbid the evil (al-amr bi’l ma’ruf wa’l nahyu ‘ani’l munkar).
7. He must accompany his prayers with the appropriate natural and supernatural means at his disposal (that is to say, his prayers should not issue from laziness and farfetched hopes).
8. He should have no unfulfilled obligations to people.
9. He must be wont to fulfil all promises and pledges.
Occasionally, it occurs that despite the fact that none of the aforementioned conditions is fulfilled, a prayer is answered or the intercession of an Imam (ع) is accepted. The philosophy behind such an apparently unwarranted acceptance might be one of several things:
1. It might be to soften the person’s heart by showing him divine grace.
2. Perhaps it is to fulfil the divine call (itmam al-hujjah) upon a person. In the extreme circumstances surrounding sickness, when all natural means seem to fade away, the favours of Allah (awj) and in turn the Prophet’s family (ع), increase, thereby closing the doors of doubt to even the greatest sophist. If this person, after experiencing divine grace, returns to his past improprieties, he will be left with no excuse on the Day of Judgment.
3. It is also possible that Allah’s (awj) acceptance of this person’s supplications was a reward for a past act of goodness or an act of devotion with respect to one of Allah’s (awj) saints in such a way as to take the place of the person’s reward in the next life.
In conclusion, it is important to keep in mind that one must not look to prayer and intercession as a last resort to be used only when all hope in natural causes—and in particular medical treatment—fades, only to be forgotten when treatment is successfully achieved. This kind of misappropriation is treated with severity in the Qur`an and ahadith[3]. If one were to make such an opportunistic use of supplication, his prayers may be answered and full health might be restored; however, in the afterlife, he would be severely punished, since despite experiencing divine grace, he turned away from Allah after being cured.
On the other hand, one must never lose hope. As Imam Ja’far b. Muhammad as-Sadiq (ع) has said, “Allah refuses to make things happen except through (their) causes.”[4]
Allah (awj) is the Cause of all causes, however, just as He is the Cause of all causes, He can also destroy all causes as evidenced by the knife that did not cut Isma’il’s (ع) throat or the fire that did not burn Ibrahim (ع). Other times, without any material cause, Allah (awj) acts independently through unseen causes as is evidenced by the story of the camel of Salih(ع) and the staff of Musa (ع). In short, while we make use of all natural causes at our disposal, it is advisable to maintain an active relationship with Allah (awj) through supplications, and with Allah’s (awj) friends.
[1] Or “Ha’ir,” a radius of about 357 metres around the shrine of the Noble Imam.
[2] Bihar al-Anwar, vol. 98, pg. 132:
فَإِذَا أَکَلْتَ مِنْ طِینِ قَبْرِ الْحُسَیْنِ ( ع) فَقُلْ: أَللٌّهُمَّ إِنِّی أَسْأَلُکَ بِحَقِّ الْمَلَکِ الَّذِی قَبَضَهَا وَ بِحَقِّ النَّبِیِّ الَّذِی خَزَنَهَا وَ بِحَقِّ الْوَصِیِّ الَّذِی هُوَ فِیهَا أَنْ تُصَلِّیَ عَلَى مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ أَنْ تَجْعَلَ لِی فِیهِ شِفَاءً مِنْ کُلِّ دَاءٍ وَ عَافِیَةً مِنْ کُلِّ بَلاَءٍ وَ أَمَاناً مِنْ کُلِّ خَوْفٍ بِرَحْمَتِکَ یَا أَرْحَمَ الرَّاحِمِینَ وَ صَلَّى اللَّهُ عَلَى مُحَمَّدٍ وَ آلِهِ وَ سَلَّمَ. وَ تَقُولُ أَیْضاً: أَللٌّهُمَّ إِنِّی أَشْهَدُ أَنَّ هَذِهِ التُّرْبَةَ تُرْبَةُ وَلِیِّکَ صَلَّى اللَّهُ عَلَیْهِ وَ أَشْهَدُ أَنَّهَا شِفَاءٌ مِنْ کُلِّ دَاءٍ وَ أَمَانٌ مِنْ کُلِّ خَوْفٍ لِمَنْ شِئْتَ مِنْ خَلْقِکَ وَ لِی بِرَحْمَتِکَ.
[3] Surat Luqman (31), Verse 32:
} وَإِذَا غَشِیَهُمْ مَوْجٌ کَالظُّلَلِ دَعَوُا اللَّهَ مُخْلِصِینَ لَهُ الدِّینَ فَلَمَّا نَجَّاهُمْ إِلَى الْبَرِّ فَمِنْهُمْ مُقْتَصِدٌ وَمَا یَجْحَدُ بِآیَاتِنَا إِلاَّ کُلُّ خَتَّارٍ کَفُورٍ {
See also: Surat al-’Ankabut (29), Verse 65; Surat Yunus (10), Verses 12, 22 & 23
[4] al-Kafi,vol. 1, pg. 183:
عَنْ أَبِی عَبْدِ اللٌّهِ ( ع) أَنَّهُ قَالَ: أَبـى اللٌّهُ أَنْ یَجْرِیَ الأَشْیَاءَ إِلاَّ بِأَسْبَابٍ...
source : islamquest.net