Riyad as-Salihin: The Book of the Etiquette of Sleeping, Lying and Sitting etc – Hadith No. 163 — Jabir (May Allah be pleased with him) reported: Messenger of Allah (ﷺ) said… (Hadith No. 163)

Jabir (May Allah be pleased with him) reported: Messenger of Allah (ﷺ) said, "When one of you sees a bad dream let him blow three times on his left, seek refuge in Allah from the Satan three times (i.e., by saying: A'udhu billahi minash-Shaitanir-Rajim) and change the side on which he was lying.".

Explanation:

Reference: Riyad as-Salihin, The Book of the Etiquette of Sleeping, Lying and Sitting etc, Hadith No. 163