“Israel sent messengers to Siḥon, king of the Emorites, saying” (Numbers 21:21). “Israel sent messengers” – this is what the verse said: “Trust in the Lord and perform good; dwell in the land and cultivate faith” (Psalms 37:3), and it says: “Turn away from evil and perform good; seek peace and pursue it” (Psalms 34:15). But the Torah did not insist upon pursuing mitzvot, but rather: “If a bird’s nest should happen before you” (Deuteronomy 22:6); “if you encounter [your enemy’s ox]” (Exodus 23:4); if you see – “if you see a donkey” (Exodus 23:5); “when you beat your olive tree” (Deuteronomy 24:20); “when you harvest your vineyard” (Deuteronomy 24:21); “when you enter another’s vineyard” (Deuteronomy 23:25).
If they present an opportunity, you are commanded in their regard, but not to pursue them. But peace, “seek peace” – in your place; “and pursue it” – elsewhere. This is what Israel did. Although the Holy One blessed be He said to them: “Begin taking possession, and provoke war with him” (Deuteronomy 2:24), they pursued peace: “Israel sent messengers to Siḥon.… let me pass” (Numbers 21:21–22).81The verse as quoted here in Hebrew includes the word “please [na].”
It does not appear in the actual verse. It does appear in Judges 11:17, regarding a similar message sent to the king of Edom.