Yosef Karo, Translation:Shulchan Aruch — Orach Chaim 30Time to Put on Tefillin
“ One is prohibited to put Tefillin on at night since he may forget [that he has them on] and sleep in them. If he puts them on before the sun sets and it happens to get dark, even if he wears them the whole night, it is permitted. [However] we do not teach [people] to do this. If he did not remove the Tefillin once the sun set since he had no place to guard them and therefore, left them on to protect them... ”
