Musannaf Ibn Abi Shaybah

Hazrat Abu Hamza narrates that once I was traveling on my mount in a state between sleep and wakefulness when I felt arousal. I denied my self, but a little fluid was discharged from me, which moistened the root of my thigh, and nothing else happened. I asked Hazrat Ibn Abbas (may Allah be pleased with them both) about this, and he said: Wash your private part and the place where you feel wetness. He did not instruct me to perform ghusl (ritual bath).