What are the facts that indicate that the greeting of the mosque is not obligatory?

Question : The question. The mosque is the place, the obligation is the default.

Answer : This questioner asks: What are the facts that indicate that the greeting of the mosque is not obligatory? They cited evidence for this by several matters. First, that the Prophet (peace and blessings be upon him) would enter the mosque on Friday, ascend the pulpit, and sit between the two sermons without praying. They also cited the hadith of Ka'b ibn Malik when he entered the mosque after Allah accepted his repentance.
He did not pray in the mosque, but this could be because he was not in a state of ritual purity, for one who enters without wudu' does not pray, and how can he pray when he is not in a state of wudu'? They also cited the story of the three men who entered while the Prophet (peace and blessings be upon him) was among them; some entered the circle, some were shy and sat behind the circle, and some left.
The Prophet (peace and blessings be upon him) did not order them to pray. So the point is that there are facts that cause a person to pause regarding the obligation, or to lean toward the view that it is not obligatory.