Why did Al-Albani, Ibn Uthaymeen, and Ibn Baz hold the view that it is not from the Sunnah to solemnize marriage in the mosque, even though there is a hadith indicating that the Prophet (peace be upon him) married off a Companion in the mosque by saying: "We have married her to you for what you have of the Qur'an"?

The aforementioned Hadith (definition) was narrated by Al-Bukhari and Muslim. Another narration, outside of the Two Sahihs, mentioned by Al-Hafiz Ibn Hajar, states that the incident took place in the mosque, which implies the permissibility of conducting a marriage contract therein, not its desirability. This is the view of the Malikis, while the majority of scholars hold it to be desirable. This issue is a matter of jurisprudential difference, where a student of knowledge acts upon what he finds more preponderant, and a layman acts upon the قول (saying/opinion) of someone whose knowledge he trusts, in accordance with the Almighty’s saying: ﴿So ask the people of the message if you do not know.﴾