Halakhah su Levitico 10:8

One must be clearheaded when she prays. Unlike many idol worshipers, who perform their rituals using drugs and alcohol to attain a state of ecstasy, our petitions to God are achieved through seriousness and deep thought. That is why the Torah commands the kohanim not to enter the Temple and perform the Divine service while inebriated (Vayikra 10:8-11). The Sages derive from this that one who is drunk or tipsy may not pray.