Is a man sinful if he intentionally thinks about lust, or kisses his wife and pre-ejaculates just before prayer in the mosque, knowing beforehand that he will pre-ejaculate? What should he do if he pre-ejaculates? Should he stay home and pray there after the pre-ejaculate stops, or should he go to the mosque, perform ablution, and pray even if the discharge of pre-ejaculate has not yet stopped?

A person is not sinful for thinking. The general rule is that a man is permitted to enjoy his wife at all times, and it is not prohibited except where the Sharia has prohibited it, such as if he fears missing the prayer time or missing the congregational prayer.

If a man touches his wife and madhiy (pre-seminal fluid) is discharged from him, he must wait until its discharge ceases, then perform ablution (wudu') and pray. He must pray in congregation if he is able to do so.