Muḥammad ibn Abī ʻAdī narrated to us from Ḥumayd, from Anas, that the Prophet (ﷺ) ﷺ was praying one night in his chamber, and some people came and prayed following his prayer. He shortened it, then entered the house, then came out; he did this several times, praying each time. In the morning they said, “Messenger of Allah, you prayed, and we would have liked you to prolong your prayer.” He said, “I knew you were there, and I did that deliberately.” Reference: Musnad Aḥmad 92