Or HaChaim on Numbers 5:12/אור החיים על במדבר ה׳:י״ב

1 דבר..ואמרת..איש איש, speak..and say.."any man whose wife is unfaithful, etc." Why did the Torah write both "speak," and "say"? Why did it use different words for the same thing, i.e. דבר, אמר? Why is the word איש repeated? A Sotah, a woman suspected of marital infidelity by her husband, may belong to either one of two categories. Either the suspicion is found to have been unjustified, or 2) she is found guilty either by her own admission or by having brazenly drunk the מים המאררים, the waters of bitterness. This accounts for the Torah employing two different words for "say!" The harsher דבור is intended for the woman who is guilty, whereas the softer אמרת is addressed to the woman who turns out to have been faithful though she gave cause for suspicion. The word איש is repeated for the same consideration. At the time her husband accuses her he does not know yet if his suspicions are justified. If the woman is innocent G'd will help her to prove her innocence. We find a popular proverb in Megillah 12 which suggests that the words ומעלה בו מעל could be interpreted to mean "if he (the husband) were guilty of a trespass" i.e. both husband and wife may be guilty of infidelity. As a result our sages stated that if the husband is certain that he has not sinned at all in his marital relations he is entitled to resume relations with his wife after she has undergone the procedure of the "bitter waters" and has been vindicated. The "bitter waters" actually examined the husband as well, i.e. the procedure did not work, the miracle would not take place if the husband himself were found guilty of marital trespass. The word איש is repeated to teach us that regardless of whether the husband knows himself to be pure or not, he still has to bring his wife to the priest.

2Perhaps our verse referred to this idea when writing both דבר and ואמרת. A husband who is himself not blameless may be afraid to have his wife examined by the priest and the bitter waters as his own shortcomings would be exposed both in the eyes of G'd and that of his peers. As a result, he might prefer not to publicise his suspicions of his wife. On the other hand, even if this husband feels certain that his own conduct was always completely blameless he may not wish to expose marital friction between himself and his wife in public. For these various reasons he might balk at the duty the Torah imposes upon him here. The Torah therefore uses a "carrot and stick" approach" i.e. with soft urgings and with tough talk so that he would comply with the legislation in our paragraph.