Musannaf Ibn Abi Shaybah

Hazrat Abdur Rahman bin Harmalah says that a man came to Hazrat Saeed bin Musayyib and said, "I am a shepherd of camels. I search for them and when evening comes, I perform the Maghrib prayer. Then I give rest to myself and then I fall asleep before the Isha prayer." He (Saeed bin Musayyib) said, "Do not sleep before performing the Isha prayer. If you fear sleep, then combine both prayers."