申命記 23:12

והיה לפנות ערב BUT IT SHALL BE WHEN EVENING COMETH ON, [HE SHALL LAVE HIMSELF WITH WATER] — He should immerse himself close before the setting of the sun, for under no circumstances is he clean without having waited for the sunset (cf. Sifrei Devarim 256:2).

וְהָיָ֥ה לִפְנֽוֹת־עֶ֖רֶב יִרְחַ֣ץ בַּמָּ֑יִם וּכְבֹ֣א הַשֶּׁ֔מֶשׁ יָבֹ֖א אֶל־תּ֥וֹךְ הַֽמַּחֲנֶֽה׃

but it shall be, when evening comes on, he shall bathe himself in water: and when the sun is down, he shall come into the camp again.