Allah forbade His believing servants from praying while drunk, for one does not know the meaning of what he is saying in that state, and He forbade them from attending the Masjids while sexually impure, except when one is just passing through the Masjid from one door to another. This Ayah was revealed before alcohol consumption was completely prohibited, as evident by the Hadith that we mentioned in Surat Al-Baqarah when we explained Allah's statement,

﴿يَسْـَلُونَكَ عَنِ الْخَمْرِ وَالْمَيْسِرِ﴾

(They ask you about alcoholic drink and gambling). In that Hadith, the Messenger of Allah recited this Ayah to `Umar, who said, "O Allah! Explain the ruling about Khamr (intoxicants) for us in a plain manner.'' When this Ayah ﴿4:43﴾ was revealed, the Prophet recited it to `Umar, who still said, "O Allah! Explain the ruling about Khamr (intoxicants) for us in a plain manner.'' After that, they would not drink alcohol close to the time of prayer. When Allah's statement,

﴿يَـأَيُّهَا الَّذِينَ آمَنُواْ إِنَّمَا الْخَمْرُ وَالْمَيْسِرُ وَالاٌّنصَابُ وَالاٌّزْلاَمُ رِجْسٌ مِّنْ عَمَلِ الشَّيْطَـنِ فَاجْتَنِبُوهُ لَعَلَّكُمْ تُفْلِحُونَ ﴾

(O you who believe! alcoholic drinks, gambling, Al-Ansab, and Al-Azlam are an abomination of Shayatan's handiwork. So avoid that in order that you may be successful. ) ﴿5:90﴾, until,

﴿فَهَلْ أَنْتُمْ مُّنتَهُونَ﴾

(So, will you not then abstain) ﴿5:91﴾ was revealed, `Umar said, "We abstain, we abstain.'' In another narration, when the Ayah in Surat An-Nisa' was revealed,

﴿يَـأَيُّهَا الَّذِينَ ءَامَنُواْ لاَ تَقْرَبُواْ الصَّلَوةَ وَأَنتُمْ سُكَـرَى حَتَّى تَعْلَمُواْ مَا تَقُولُونَ﴾

(O you who believe! Do not approach Salah while you are in a druken state until you know what you are saying,) at the time of prayer, the Messenger of Allah would have someone proclaim; "Let not any drunk approach the prayer.'' This is the wording collected by Abu Dawud.