Sunan Ibn Majah 1509
سنن ابن ماجه#1509Da'ifحَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا الْبَخْتَرِيُّ بْنُ عُبَيْدٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ النَّبِيُّ ـ صلى الله عليه وسلم ـ " صَلُّوا عَلَى أَطْفَالِكُمْ فَإِنَّهُمْ مِنْ أَفْرَاطِكُمْ " .
It was narrated that Abu Hurairah said:“The Prophet (ﷺ) said: ‘Offer the (funeral) prayer for your children, for they have gone ahead of you (i.e. to prepare your place in Paradise for you).”
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniVery Daif
Muhammad Fouad Abd al-BaqiVery Daif
Shuaib Al ArnautVery Daif
Zubair Ali ZaiDaif
In-book reference: 6:77