A foster-child of Ayesha reported on the authority of Ayesha that the Prophet ﷺ said, "No Muslim dies and a community of people numbering up to a hundred prays over him, interceding for him, without their intercession being accepted on his behalf."
حدثنا إسماعيل حدثنا أيوب عن أبي قلابة
رضيعا كان لعائشة عن عائشة رضي الله عنها أن النبي ﷺ قال لا يموت أحد من المسلمين فيصلي عليه أمة من الناس يبلغون أن يكونوا مائة فيشفعوا له إلا شفعوا فيه
Its isnad is sahih. Abdullah bin Yazid, the foster brother of Ayesha, is reliable, and his hadith appears in Muslim. The hadith was also narrated by Tirmidhi 3/339 no. 1029, who said, hasan sahih, and by Nasai 4/76 no. 1992.