He heard the Messenger of Allah ﷺ say, "Do not pray toward graves, nor sit upon them."
حدثنا الوليد بن مسلم قال سمعت ابن جابر يقول حدثني بسر بن عبيد الله الحضرمي أنه سمع واثلة بن الأسقع صاحب رسول الله ﷺ يقول حدثني
سمع رسول الله ﷺ يقول لا تصلوا إلى القبور ولا تجلسوا عليها
Its isnad is sahih. Ibn Jabir is Abdul-Rahman bin Yazid bin Jabir, and Busr bin Ubaydullah, or Abdullah, Hadrami, are both reliable and precise narrators.The hadith was narrated by Muslim, 2/668, no. 972, in the Book of Funerals, on the prohibition of sitting on a grave, and by Abu Dawud, 3/217, no. 3229, and Tirmidhi, 3/359, no. 1051, and Nasai in the qibla, 2/67, no. 760. Hakim graded it sahih, 3/220.