Musnad Ahmad 1153:2358

Al-Walid ibn al-Qasim ibn al-Walid narrated to us, he said: Isra'il narrated to us, from Mansur, from Ibrahim, from al-Aswad, from Aisha, she said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "There is no Muslim who is pricked by a thorn, or anything above it, except that Allah raises him a degree by it, and removes a sin from him by it."