Musnad Ahmad 1153:1411

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from 'Amr ibn Murrah, he said: I heard Abu Wa'il narrating from 'Aishah, 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 greater than it, except that Allah, the Mighty and Majestic, raises him a degree by it, or removes a sin from him by it."