Fear one should have about breaking relations

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."

Rights of the Relatives and the Ease in Reckoning

The Creator of the Universe, Almighty Allah remarks in the Holy Quran:
"Certainly Allah orders equity, kindness (to people) and the giving (of what they need) to the relatives." 
(Surah Nahl 16:90)

In Surah Raad is the following verse:
"And those who join that which Allah has bidden to be joined and have awe of their Lord and fear the evil reckoning." 
(Surah Raad 13:21)

The expression 'reckoning' in this Ayat denotes the accounting of one's deeds with regard to his duty of kindness towards relatives. This Ayat shows that kindness towards the kith and kin shall be an important factor to ease the difficulty of the accounting for one's deeds.

Imam Ja'far as-Sadiq (a.s.) explains as follows:
"Kindness to relatives makes the reckoning (of the Hereafter) easy." 
(Behaarul Anwaar)

The Inimical Relative of Imam Ja'far as-Sadiq (a.s.)

Imam Ja'far as-Sadiq (a.s.) made a will in his last moments: 
"Pay seventy Dinars to my paternal cousin Hasan Aftas."

He was asked, "Master you are making a gift to someone who has attacked you with a sword?"

Imam (a.s.) replied, 
"Do you think I should not be included among those concerning whom the Quran says: 
'And those who join that which Allah has bidden to be joined and have awe of their Lord and fear the evil reckoning…" 
(Surah Raad: 13:21)

Allah has created Paradise, purified it and made it fragrant. Its fragrance is felt at a distance of two thousand years (of travel). But the one who disobeys his parents or breaks ties with the kin will be so far away from Paradise, that he will not even experience its fragrance. 
(Behaarul Anwaar)

Traditions Regarding Kindness to Relatives

There are numerous traditions to the fact that Sileh Rahmi is obligatory. In one of such traditions Imam Baqir (a.s.) relates from the Holy Prophet (s.a.w.s.) that he said:
"I will (command) all the people of my Ummat, whether present or not, and those generations which are to come till the Qiyamat, who are still in the loins of their father and wombs of their mothers, that they should be kind to their relatives (and visit them) even if they live at a distance of a year's journey. Because kindness to relatives is one of the commands which is made an integral part of the faith (Imaan)."

One Who is Kind to the Relatives Will be Able to Cross the Bridge of Siraat Smoothly

Imam Muhammad al-Baqir (a.s.) relates from Hazrat Abu Zar Ghaffari (r.a.) who quotes the Holy Prophet (s.a.w.s.) to have remarked:
'Siraat (the bridge passing over Hell that everyone has to cross) will have on each side (of it) 'Sileh Rahmi' and 'Amanat' (keeping a trust) one who performs the act of Sileh Rahmi and maintains trusts (Amanat) shall be able to cross the 'Siraat' easily and will reach Paradise.

None of the good deeds will benefit those who have broken ties with relatives or committed breach of trust. They will slip from the bridge of 'Siraat' and drop into Hell-fire. 
(Al Kafi)