Musannaf Ibn Abi Shaybah

A man from the tribe of Thaqif narrates that a person from Banu Thaqif consulted Hazrat Umar about spreading grass in the mosque. He said, "O Commander of the Faithful, this is a more comfortable thing, and it hides spit and filth, etc." Hazrat Umar replied, "Spread the grass of the blessed valley, that is, the valley of Aqeeq, in the mosque." Thus, Hazrat Umar was the first to spread grass in the mosque.