Hadithcore
Bulugh al-Maram, 571

Umm ‘Atiyah (RAA) narrated, ‘We were forbidden to accompany funeral processions, but this prohibition was not mandatory for us.’ Agreed upon.

وَعَنْ أُمِّ عَطِيَّةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: { نُهِينَا عَنِ اتِّبَاعِ الْجَنَائِزِ, وَلَمْ يُعْزَمْ عَلَيْنَا } مُتَّفَقٌ عَلَيْه ِ [1]‏ .‏

References2 variants
In-Book Reference
Book 3, Hadith 40
English Reference
Book 3, Hadith 596