Surah 4. An-Nisaa', Ayah 43

I.e., after sexual intercourse. The term junub (rendered by me as "in a state requiring total ablution") is derived from the verb janaba, "he made [a thing] remote", and signifies one's "remoteness" from prayer because of immersion in sexual passion.

Lit., "if one of you comes from the place in which one satisfies...", etc.

This symbolic ablution, called tayammum, consists in touching the earth, or anything supposed to contain dust, with the palms of one's hands and then passing them lightly over face and hands. Whenever water is not within reach - or cannot be used because of illness - the tayammum takes the place of both the total ablution after sexual intercourse (ghusl) and the partial ablution before prayers (wudu').

The reference to prayer at this place arises from the mention, in the preceding verses, of the Day of Judgment, when man will have to answer before God for what he did during his life in this world: for it is in prayer that man faces God, spiritually, during his earthly life, and reminds himself of his responsibility towards the Creator. As regards the prohibition of attempting to pray "while in a state of drunkenness", some of the commentators assume that this ordinance represented the first stage of the total prohibition of intoxicants, and has been, consequently, "abrogated" by the promulgation of the law of total abstinence from all intoxicants ( 5:90 ). However, quite apart from the fact that the doctrine of "abrogation" is entirely untenable (see surah {2}, note [87]), there is no warrant whatever for regarding the above verse as a "first step" which has become redundant, as it were, after total prohibition was ordained. It is, of course, true that the Qur'an forbids the use of intoxicants at all times, and not merely at the time of prayer; but since "man has been created weak" ( 4:28 ), his lapse from the way of virtue is always a possibility: and it is to prevent him from adding the sin of praying while in a state of drunkenness to the sin of using intoxicants as such that the above verse was promulgated. Moreover, the expression "while you are in a state of drunkenness (sukara)" does not apply exclusively to alcoholic intoxication, since the term sukr, in its wider connotation, signifies any state of mental disequilibrium which prevents man from making full use of his intellectual faculties: that is to say, it can apply also to a temporary clouding of the intellect by drugs or giddiness or passion, as well as to the state metaphorically described as "drunk with sleep" - in brief, to any condition in which normal judgment is confused or suspended. And because the Qur'an insists throughout on consciousness as an indispensable element in every act of worship, prayer is permitted only when man is in full possession of his mental faculties and "knows what he is saying".

 Intoxicants were prohibited in the Quran in three stages: 2:219, 4:43, and finally 5:90-91.

 i.e., after sexual intercourse or a wet dream.

 This ruling is called tayammum or ‘dry ablution.’ If someone cannot find water or is unable to use it because of illness or cold weather, then they are allowed to touch clean earth, sand, etc. with the palms of their hands once then blow in their hands and wipe over their face and hands.

The reference is either to a state of intoxication or to a dazed state of mind on account of drowsiness or some other cause. Or perhaps both are implied. Before the prohibition of intoxicants altogether was promulgated, it was at least unbecoming that people should come to prayers in such a state. For prayers it is only right that we should collect our whole minds and approach Allah in a spirit of reverence.

The strictest cleanliness and purity of mind and body are required, especially at the time of prayer. But there are circumstances when water for ablutions is not easily obtainable, especially in the dry conditions of Arabia, and then washing with dry sand or clean earth is recommended. Four such circumstances are mentioned: the two last when washing is specially required; the two first when washing may be necessary, but it may not be easy to get water. For a man, when he is ill, cannot walk out far to get water, and a man on a journey has no full control over his supplies. In all four cases, where water cannot be got, cleaning with dry sand or dry earth is recommended. This is called Tayammum.