the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
A hadîth is narrated in Musnad Ahmad (21163), Sunan al-Bayhaqî (3/409), and Mustadrak al-Hâkim (3390) that when the Prophet (peace be upon him) buried Umm Kulthûm, he recited verse "From it We created you, and into it We shall send you back, and from it will We raise you a second time." [Sûrah TâHâ: 55].
The hadîth is weak at best. Moreover, it does not indicate in any way that the Prophet (peace be upon him) recited the three phrases of the verse in conjunction with a separate toss of a handful of dirt.
Al-Albânî says in Ahkâm al-Janâ'iz (1/153):
The hadîth does not indicate the supposedly preferable division of phrases, even if it had an authentic line of transmission… The hadîth is extremely weak. Indeed, Ibn Hibbân declares it to be a fabrication.
Therefore, the practice is not established by textual evidence.
And Allah knows best.
Source: Islam Today