Hadith 6:1142
Hushaym narrated to us, he said: Ibn ‘Awn informed us, he said: I was with Ibn Sirin, and we were intending [to attend] a funeral. We were preceded by it until it was buried. He said: So Ibn Sirin said, "Come, so that we may do as they did." He said: So he performed four takbirs over the grave.
حدثنا هشيم قال أخبرنا بن عون قال كنت مع بن سيرين ونحن نريد جنازة فسبقنا بها حتى دفنت قال فقال بن سيرين تعال حتى نصنع كما صنعوا قال فكبر على القبر أربعا