When the members of his family were asleep, the Holy Prophet (sa) would get up quietly and occupy himself in prayer and worship. A’ishah (ra) relates that once she woke up during the night and found him absent. She thought that the Holy Prophet (sa) had gone to some other wife. Searching for him she found him prostrating. There was mud on his forehead and he was on ground praying:
‘O Allah, Holy art Thou with Your praise. There is none worthy of worship except You.’
Seeing this she felt remorseful at her presumption that the Prophet (sa) of God was in another world while she was entertaining doubts in her mind.
At night when everyone would be asleep, the Holy Prophet (sa) would quietly leave and go to a desolate graveyard and engage in supplication. Once out of curiosity A’ishah (ra) followed him; he was standing in Jannat al-Baqi‘ [graveyard] and was busy offering endearments to his Lord. He said to A’ishah (ra), ‘Why did you think that I am being cruel to you (meaning going to another wife)?’ and then said, ‘Gabriel encouraged me to come and pray for forgiveness for the people buried in Jannat al-Baqi‘. I thought you were asleep so I did not wake you up.’
Muhammad (sa) – The Perfect Man (Qadian, India: Nazarat Isha‘at, 2015), 79.