Musnad Ahmad 334:23

Yunus narrated to us, he said: Al-Attaf narrated to us, he said: Abd al-Rahman narrated to me—and someone other than Yunus said: Ibn Razin—that he stopped at al-Rabadhah, he and companions of his, intending to perform Hajj. It was said to them: "Here is Salamah ibn al-Akwa', a companion of the Messenger of Allah, may Allah bless him and grant him peace." So we came to him and greeted him, then we asked him, and he said: "I pledged allegiance to the Messenger of Allah, may Allah bless him and grant him peace, with this hand of mine." And he brought out for us his palm, a massive palm. He said: So we stood up to him and kissed his palms, all of us.