Musnad Ahmad 27:1150

Nafi’ said: Abdullah ibn Umar narrated to him that the Messenger of Allah (peace and blessings of Allah be upon him) stopped under a *sarhah* tree—and someone other than Abu Qurrah said: *sarhat* (plural)—to the left of the road, in a watercourse below Harsha. That watercourse is adjacent to Harsha—and someone else said: adjacent to the ridge of Harsha—and between it and the road is about the distance of an arrow shot.