Musannaf Ibn Abi Shayba 3:1890

Waki’ narrated to us, from Mus’ab ibn Shaybah, from Sa’id ibn Jubayr, who said: I saw al-Dahhak ibn Qays prostrating in [Surah] Sad. He said: So I mentioned that to Ibn Abbas, and he said: "He saw Umar ibn al-Khattab prostrating in it."