Comentario citado sobre Números 5:19

אלו נאמרין. פרשת סוטה – as it is written (Numbers 5:19): “[The priest shall adjure the woman,] saying to her, [“If no man has lain with you, if you have not gone astray in defilement while married to your husband, be immune to harm from this water of bitterness that induces the spell].” In any language that he states it.

The following may be recited in any language:
the section concerning the sotah, The first is the oath that the priest makes a sotah swear (Numbers 5:19-23). The Talmud derives this by using a midrash. It may also be that since the sotah has to understand what she is swearing to, if she doesn’t understand Hebrew it can be recited in any language that she does understand. This rationale lies behind most, if not all, of the other recitations listed in this mishnah.

Gemara. We choose the textual variant: "And he shall say to the woman” [Numbers 5:19] -- in any language that she understands [Sifrei Bamidbar 12:1]; the Sifrei derives it from this verse. We do not choose the textual variant "And the priest shall say to the woman" [Numbers 5:21].