A companion of Imam Ja'far as-Sadiq (a.s.) complained about the ill-treatment given to him by his relatives,
"My own brother as well as my paternal cousins are harassing me. They have snatched the house that rightfully belonged to me and have given me only a room to live in. If I complain to the government, I shall be able to recover all my property.
Imam (a.s.) said,
"Be patient, everything will be alright."
The man returned satisfied. In the year 131 A.H. there was a terrible plague. All the relatives of the man perished. Thereafter when he arrived before Imam Ja'far as-Sadiq (a.s.), he (Imam a.s.) asked,
"How are your relatives?"
The man said, "By Allah all of them are dead." The Imam (a.s.) said,
"Their deaths have been due to their ill-treatment and Qat-e-Rahmi of relatives like you, not recognizing your right and cutting off relationships."
Bereft of Divine Mercy
Imam Ja'far as-Sadiq (a.s.) relates from the Holy Prophet (s.a.w.s.) that he said:
"When people claim to possess knowledge but do not act upon it, when they claim to profess love but harbour malice in their hearts and sever relations, in such a condition Allah removes mercy from them and makes them undiscerning to logic.
The Holy Prophet (s.a.w.s.) says:
"Among the various sins, injustice and cutting off relationships are such that one who commits these is punished in this world itself. Apart from this the punishment for these sinners has already been prepared in the Hereafter."
At another occasion the Holy Prophet (s.a.w.s.) has informed:
"One who severs relationships will not enter Heaven."
Jabir Ibne Abdullah Ansari (r.a.) has related from Imam Muhammad al-Baqir (a.s.) that he quotes the Holy Prophet (s.a.w.s.) as follows:
"Jibraeel (a.s.) has informed me that even at a distance of a thousand years man will be able to smell the fragrance of Heaven , but one who disobeys his parents, the one who breaks ties with the kith and kin, or the aged adulterer will not be able to smell it. In fact, the fragrance of Paradise will be felt even at a distance of two thousand years, but not by those who disobey their parents and those who break ties with the relatives."
The exalted Prophet of Islam (s.a.w.s.) has also informed that the invocation of the person who breaks family ties shall not be answered. "In the chapter on the merits of Shab-e-Qadr the Prophet (s.a.w.s.) has stated that in the night of Qadr Allah forgives the sins of all the people except of those who drink wine, who disobey their parents, and those who break ties with the relatives or harbour enmity towards the believers."
Kindness to Relatives is Obligatory
The Almighty Allah says in the Quran:
"...and be cautious of (your duty to) Allah, by Whom you demand one of another (your rights), and (to) the ties of relationship;"
(Surah Nisa 4:1)
According to Imam al-Baqir (a.s.), the notable point in this verse is that the fear of Allah is mentioned alongwith the fear one should have about breaking relations with kith and kin.
In the book Al Kafi there is a tradition from Imam Ja'far as-Sadiq (a.s.). He says:
"The relatives in this Ayat, include all, and not only the nearest ones. Certainly Allah has ordered kindness towards all the relatives. Allah has given so much importance to this deed that he mentions it with his exalted name."
Kindness to Relatives is Commanded in the Same Way as Namaz and Zakat
It is related from Imam Ali-ar-Reza (a.s.):
"Allah has ordered three things along with three others, in the glorious Quran:
1) Namaz is ordered along with Zakat. If one offers Namaz but does not pay Zakat (when it is due upon him) then his Namaz will not be accepted.
2) Allah has ordered thankfulness to Himself along with the thankfulness to one's parents. If one is not grateful to one's parents it is as if he has not been grateful to Allah.
3) Allah has ordered piety along with kindness to ones kith and kin. Then one who is not kind towards the relatives is not pious."
source : GREATER SINS by Ayatullah-ul-Uzma Sayed Abdul Husain Dastghaib Shirazi (r.a.)