I said to Abu Abdullah (as): (What about) the Words of Allah (swt) in the Holy Qura’an: “O you who believe! Do not approach the Salat while you are intoxicated [4:43]”? So he (as) said: (It is) the intoxication of the sleep.
[Al Kafi 3: 15/371]
I asked the 5th Imam (as) about the words of Allah (swt) “O you who believe! Do not approach the salat while you are Intoxicated until you know what you are saying [4:43]. He (as) said: Meaning the intoxication of the sleep, while there is drowsiness with you, and you should be knowing what you are saying during your Rukus and Sajdahs and your exclamations of Takbeers.
He further said: And it isn’t like what a lot of the people are claiming that the Momin gets intoxicated from the drink. And the Momin neither drinks the intoxicants nor does he get drunk.
[Tafseer Ayyashi, 1: 137/242]
Abu Ja’far (as) said: Do not stand for the salat sluggishly, nor drowsily, nor (with) heaviness, for these are from the traits of hypocrisy, for Allah (swt) has forbidden the Momineen that they should be standing up for the Salat and they are intoxicated, meaning from the sleep.
[Tafseer Ayyashi, 1: 134/242]