Musnad Abu Ya'la al-Mawsili 154:59

Zakariya ibn Yahya narrated to us, Hushaym narrated to us, from ‘Ata’ ibn al-Sa’ib, who said: ‘Abdullah ibn ‘Ubayd ibn ‘Umayr narrated to me that he heard his father saying to Ibn ‘Umar: “Why do I see you touching these two corners and not touching any others?”—meaning the Black Stone and the Yemeni Corner. He said: “If I do so, it is because I heard the Messenger of Allah (ﷺ) say: ‘Indeed, touching them removes sins.’ And no man lifts a foot nor places it down except that ten good deeds are written for him, and ten evil deeds are removed from him.” And I heard him say: “Whoever completes a circuit (tawaf) and prays two rak’ahs, it is like the freeing of a slave.”