Musnad Ahmad 334:19

Ishaq ibn Isa and Yunus narrated to us—and this is the hadith of Ishaq—he said: Ataf ibn Khalid al-Makhzumi narrated to us, he said: Musa ibn Ibrahim narrated to me, he said: Yunus ibn Abi Rabi’ah said: I heard Salamah ibn al-Akwa’, and whenever he would stop [on a journey], he would stop at my father’s house. He said: I said, "O Messenger of Allah, I am out hunting and I have nothing on me but a shirt; should I pray in it?" He said: "Button it, even if you find nothing but a thorn."