Is it permissible to pray Fajr while experiencing intermittent سلس (urinary incontinence), and is a person considered negligent regarding Fajr prayer if sleep overwhelms them after waiting for the سلس to cease?

It is not permissible to perform Fajr prayer without the prescribed purification (purification for one who has intermittent discharge). There is no excuse for being overcome by sleep, but if sleep overcomes you once, there is no harm. Intermittent impurity may be an excuse for not attending congregational prayer. If the emission of gas is continuous such that ablution does not remain, one should perform ablution at the beginning of the time for each prayer and pray, even if it is emitted. However, if there is a time when one can pray, one should perform ablution and pray, even if that means missing the congregation. It is not permissible to waste the time of an obligatory prayer; rather, one must wake up at a time that allows for purification and prayer, with the possibility of managing sleep, using an alarm clock, or waking up before Fajr, urinating, then sleeping, then waking up for ablution and prayer.