How should one deal with the slaughtered animals of a brother who does not pray, and are his slaughtered animals considered permissible to eat?

You must advise your brother to maintain his prayers and inform him of the ruling concerning one who abandons it. You should also prevent him from slaughtering for you, because one who abandons prayer is considered an apostate whose slaughtered animal is not lawful to consume. This is supported by the Prophet's (peace be upon him) saying: "Between a man and polytheism and disbelief is the abandonment of prayer," and "The covenant between us and them is prayer; whoever abandons it has disbelieved." His statement that the two Shahadas (declarations of faith) are sufficient is a grave error, for the two Shahadas must be accompanied by the establishment of prayer and the giving of zakat. It is obligatory to be cautious about being lenient with one who abandons prayer; their slaughtered animal should not be eaten, nor should they be invited to a feast. Rather, they should be shunned until they repent and pray.