Ibn Majah

1؎: Letting the lower garment (tehband) hang below the ankles is a grave sin and there is a severe warning regarding it. In one narration, the Prophet sallallahu alayhi wa sallam ordered those who let their lower garments hang below the ankles to repeat both their prayer and their ablution (wudu). According to most scholars, this command was for emphasis and warning, because there is no reason for the ablution to be invalidated. In any case, performing prayer while the lower garment is hanging below the ankles is a serious matter, as there is a risk that the prayer may not be valid. Whoever does this out of pride and arrogance is even more deserving of warning, as he has committed two major sins. And as for the one whose lower garment sometimes falls below the ankles unintentionally, as has been reported regarding Abu Bakr radi Allahu anhu, the Prophet sallallahu alayhi wa sallam said: "You are not among those people." And letting the garment hang below the ankles is not specific to the lower garment (tehband) alone; rather, for every type of clothing, there is allowance to extend it to the Sunnah length or as much as is needed, and up to the ankles. Wearing it below the ankles is forbidden. Similarly, letting the end of the turban (shamlah) hang below the middle of the back is an innovation (bid‘ah) and forbidden, and it is extravagance.