We were forbidden from following funeral processions, but it was not made strictly binding upon us.
نهينا عن اتباع الجنائز، ولم يعزم علينا.
Bukhari narrated it in Funerals (1278), and Muslim in Funerals (938), both through Hafsa bint Sirin, mother of Huzayl, from Umm Atiya, and their wording is identical.In sources other than Sahihayn, "The Messenger of Allah ﷺ forbade us."His statement, "but he did not insist upon us," means he did not emphasize the prohibition to us as he emphasized it to us in other forbidden matters. This indicates that following funeral processions is disliked, but not forbidden.It has also been narrated in unestablished hadiths, "There is no reward for them in that."Tabarani narrated it in Dua (2161) and Ibn Hibban in Thiqat (6/493) from the hadith of Ayesha.There are other hadiths conveying the same meaning, and all of them are daif.