(by Rabbi Phil Chernovsky)
If a wife is unfaithful to her husband, and there is no proof of her adultery, or if a man suspects his wife of unfaithfulness and it be unwarranted, he may formally warn her in front of witnesses not to be seen in the company of a particular man. This warning is a precondition to the whole topic of Sota.
Suspicion alone, or even adultery per se, do not produce the conditions for Sota without a formal warning by the husband. Once the warning is issued, it is a mitzva (requirement) to proceed with the Sota-process. The husband must bring his wife to the kohen [priest] at the Beit HaMikdash [Temple]. A barley-meal offering is brought. No oil or spice is used with it since the issue at hand is so serious and unpleasant before God. Note from SSV: I’ve heard why the offering here must be plain barley meal, which is unique, I think, among the various meal-offerings in the Torah. Barley meal is very coarse and is usually an animal feed. Adultery is bestial & those guilty of it have acted like animals, who copulate by instinct and are driven by their brute impulses.
The kohen prepares a potion consisting of water from the Kiyor (the washing basin in the courtyard of the Beit HaMikdash), earth from the floor, and the dissolved writing of this portion of the Torah. The kohen administers an oath to the woman asking her to swear to her innocence, if that be the case, or to admit her guilt. The woman is warned of serious adverse effects of the potion which she will be given to drink, if in fact she has committed adultery, and of the favorable consequences of the potion if she is innocent.
(…).
There are many details, too numerous to include here, concerning the conditions necessary for the Sota-process to go though to its end. In other words, there would be many situations when the oath and potion would not be used.
One interesting and serious warning for today. The first part of Sota, namely the warning in front of witnesses, applies today, even without a Beit HaMikdash. If a man were to give the Sota-warning in front of witnesses today, and his wife subsequently is seen alone with the man named in the warning, he would be duty-bound to bring his wife to the Beit HaMikdash (a slight problem today, unfortunately) and he would be prohibited from having relations with her until then. Big problem. Easy solution: don’t do the first part, no matter what the situation.
For those of us who have been around a while, I am guessing this is the same ssv (still small voice) who has posted a lot of helpful information from a Jewish perspective.