Ammar reported,

He witnessed the funeral of Umm Kulthum and her son, and the boy was placed closer to the imam. He found this strange. Among the people present were Ibn Abbas, Abu Saeed Khudri, Abu Qatada, and Abu Hurairah, and they said, "This is the Sunnah."

Azami 3689

Sahih

عن عمار مولى الحارث بن نوفل

أنه شهد جنازة أم كلثوم وابنها، فجعل الغلام ما يلي الإمام، فأنكرت ذلك، وفي القوم ابن عباس وأبو سعيد الخدري وأبو قتادة وأبو هريرة فقالوا: هذه السنة.

الأعظمي 3689صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Funerals
Chapter
Prayer over the deceased
Section
Order of placing the bodies of men, women, and children when they are together
Numbering
Jami al-Kamil 3689 (2nd edition)
Azami 3689