TT #310 · Parashas Shoftim · Seventh Aliyah · Passuk 20:10
When you draw near to a city to fight against it, you shall call out to it for peace.
Torah Temimah points to Sifrei Devarim 199 / Sotah.
TT lemma: וְקָרָאתָ אֵלֶיהָ לְשָׁלוֹם.
Sefaria — Sifrei Devarim 199 / Sotah
English: ‘You shall call out to it for peace’ – it is a mitzvah to call for peace.
Derash establishing the obligation of a peace offer (Sifrei) — the verse creates a positive duty to offer terms before fighting.
Before attacking a city, Yisrael must first call out to it with an offer of peace.