Musannaf Ibn Abi Shayba 3:3183

Abu Bakr narrated to us, he said: Ibn Numayr narrated to us, from Juwaybir, from al-Dahhak, regarding His saying: "And when the prayer has been concluded, disperse within the land and seek from the bounty of Allah." He said: It is a permission from Allah. So when he finishes, if he wishes, he may go out, and if he wishes, he may sit in the mosque.