Through successive chain of authorities, the Noble Shaikh, Muhammad bin Nu’man al Mufeed (May Allah sanctify his spirit) relates from the Noble Shaikh Abul Qasim Ja’far bin Muhammad Qawlawayh Qummi (May Allah scent his grave), from Ibn Waleed, from Saffar, from Ibn Abul Khattab, from Muhammad bin Isma’il, from Saleh bin Aqbah, from Abu Haroon Makfoof, who says that once I went to the presence of Imam Ja’far as Sadiq (a.s.). Imam (as) told me to recite some couplets to which I started reciting.
Then Imam (a.s.) said,
“Not like this, recite as you do so for him (Imam Husayn(as)) among yourselves and (standing) on the head of his grave.”
Then I recited, “While passing by the grave of Husayn (as) tell his blessed bones…” Then Imam (a.s.) started weeping and hence I became silent. Imam Sadiq (a.s.) told me to continue and recite some more, thus I recited “O Farwa! Arise and weep and lament upon your Master Husayn (as), give an opportunity to weep over the corpse of Husayn (as).” Abu Haroon continues that Imam Sadiq (a.s.) wept bitterly and the women of his household too wept. When they became silent, Imam said,
“O Abu Haroon! If a person recites couplets about Imam Husayn (a.s.) and makes ten people weep by it then Paradise is reserved for him at that very moment.”
Then Imam started reducing the number of persons till he reached one and said,
“If a person recites couplets about Imam Husayn (a.s.) and makes a single person weep by it, then Paradise is reserved for him at that very moment.”
“Anyone who remembers Imam Husayn (a.s.) and weeps over him, shall have Paradise (as his reward).”
The author (Shaikh Abbas Qummi) says that the couplets recited by Abu Haroon were the ones composed by Sayyid al Himyari and which has been explicitly quoted by Shaikh Ibn Nima.
(Reference: Nafasul Mahmum, Forty Traditions (Ahadith) regarding the merit of mourning over the afflictions of Imam Husayn (a.s.), Hadith no. 2)