In this regard...

In this regard, Imam as-Sadiq (‘a) says to Hammad al-Basri, “The father of ‘Abdullah was killed as a stranger, away from home; he is mourned be whoever visits his gravesite, and whoever does not visit it grieves for him; whoever does not see him is very depressed on account of being deprived of doing so, therefore he grieves; whoever sees the grave of his son at his feet in a desolate land, far away from his kin, invokes Allah's mercy for him because of the fact that he was not supported when he called upon people to uphold righteousness, and because the renegades assisted one another against him till they killed him and did not have any respect for him, so much so that they exposed his corpse to the wild beasts and prohibited him from drinking of the water of the Euphrates of which the dogs drink.

They disregarded their obligations in his regard towards the Messenger of Allah (S) who had enjoined them to be kind to him and to his (‘a). He was abandoned in his grave, slain among his kinsfolk and Shi’as. In loneliness, being near his grave removes the pain of loneliness and so is his being distant from his grandfather (S)…