Narrated Anas:
Once the Iqama was pronounced and the Prophet (ﷺ) was talking to a man (in a low voice) in a corner of the mosque and he did not lead the prayer till (some of) the people had slept (dozed in a sitting posture) .
Narrated `Abdullah:
the Prophet (ﷺ) said "When three persons are together, then no two of them should hold secret counsel excluding the third person."
Narrated `Abdullah:
The Prophet (ﷺ) said, "When you are three persons sitting together, then no two of you should hold secret counsel excluding the third person until you are with some other people too, for that would grieve him."
Anas reported: (The people) stood up for prayer and the Messenger of Allah (ﷺ) was whispering to a man, and in the narration of 'Abd al-Warith (the words are): The Messenger of Allah (ﷺ) was having a private conversation with a man, and did not start the prayer till the people dozed off.