Musannaf Ibn Abi Shayba 21:415

Yazid ibn Harun narrated to us, Muhammad ibn Ishaq narrated to us, from Umarah ibn Ghaziyyah, from Yahya ibn Rashid, who said: We performed Hajj, and when we finished our rites, we said: "If only we went to Ibn Umar so that he might speak to us." So we went, and he came out to us and sat among us. He remained silent due to his rites, and we remained silent so that he would speak to us. When he prolonged the silence, he said: "What is the matter with you that you do not speak? Do you not say: 'Glory be to Allah (SubhanAllah), and praise be to Allah (Alhamdulillah), and there is no god but Allah (La ilaha illallah), and Allah is the Greatest (Allahu Akbar), and there is no power and no strength except by Allah (La hawla wa la quwwata illa billah)'? A good deed is worth ten times its like, up to seven hundred times over. For if you increase in good, Allah will increase you."