O ye who believe! Approach not prayers with a mind befogged, until ye can understand all that ye say,- nor in a state of ceremonial impurity (Except when travelling on the road), until after washing your whole body. If ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth, and rub therewith your faces and hands. For Allah doth blot out sins and forgive again and again.
Yahiya Emerick writes,
The consumption of alcohol was not forbidden in the earliest days of Islam. (See 16:67.) It was a gradual process that took several years to complete. This was no small feat given the love of alcohol that was endemic to Arabian society. Given that Islam was emphasizing self-control and righteousness, it became increasingly clear to the early Muslims that the negative effects of alcohol were hard to overcome. (See 2:219.) Thus, people began to cut back how much they drank on their own. One day in the Medinan Period, a companion named ‘Abdur-Rahman ibn ‘Awf invited some friends over for a drinking session. When prayer time came, the inebriated men arose, and the one leading the prayer misquoted a Qur’anic passage, making the verse say the opposite of what it was supposed to say. (Verse 109:2 was recited without the negation.) In a similar report, a man named Sa’d was hit in the nose during a dinner party in which the men were, likewise, inebriated. (Muslim) When the Prophet was informed of these things, God revealed this verse to him. (Tirmidhi, Razi) (Compare with Leviticus 10: 8-10.) After this verse was revealed, a man was appointed to announce after the adhan (call to prayer), “Let no drunk person attend the prayers.” Later on, alcoholic beverages were completely forbidden, and this multi-year, three-step program was ultimately successful. (See 5:90 and footnotes.) The Prophet also explained that this prohibition from praying while inebriated also extends to those who are very sleepy, and who might not know what they were reciting in their prayers. They should get some rest and then pray. (Qurtubi)
Emerick, Yahiya. The Meaning of the Holy Qur’an in Today’s English (p. 829). Unknown. Kindle Edition.