Silsilat al-Ahadith al-Sahihah

It is narrated from Nafi‘ that ‘Umar (may Allah be pleased with him) sent a military detachment and appointed over them a man called Sariyah. (It happened that) ‘Umar (may Allah be pleased with him), during the Friday sermon, said: "O Sariyah! Take to the mountain, O Sariyah! Take to the mountain." Then it was found out that Sariyah had reached the mountain at that very hour on Friday, and there was a distance of one month between them.