Is it permissible to perform Salat in a house where a girl regularly drinks alcohol, and is there any sin if the father prays in this house without being aware of that?

Drinking alcohol is a major sin. Anyone who sees someone drinking it must advise them, enjoin good, and forbid evil. Silence is not permissible, especially for those in charge, based on the Prophet's (peace be upon him) saying: "Each of you is a shepherd, and each of you is responsible for his flock." It is also not permissible to sit with him while he is drinking; rather, one should forbid him, then distance oneself, fearing that God's wrath may descend upon everyone. If one sees that shunning them would be beneficial, then one should shun them.

Prayer in a place where alcohol has been drunk is valid if all conditions and pillars are met, and if the alcohol has not contaminated one's clothes, body, or place of prayer. This is according to the majority opinion regarding the impurity of alcohol.

The questioner, if she does not pray, must establish prayer, which is the second pillar of Islam, and repent to Allah for abandoning it, for it is one of the greatest major sins. The Prophet (peace be upon him) called it disbelief: "The covenant between us and them is prayer; whoever abandons it has disbelieved." Some scholars have considered abandoning it out of laziness to be among the acts of disbelief that expel one from the religion, while abandoning it while denying its obligation is disbelief by consensus.