Parashas Shemos
וַיִּקְרָא֩ אֵלָ֨יו אֱלֹהִ֜ים מִתּ֣וֹךְ הַסְּנֶ֗ה וַיֹּ֛אמֶר מֹשֶׁ֥ה מֹשֶׁ֖ה וַיֹּ֥אמֶר הִנֵּֽנִי׃
And God called to him from within the bush and said: Moshe, Moshe. And he said: Here I am.
Torah Temimah points to TT on 3:4 (verified).
משה משה — לשון חבה, לשון זירוז.
English: “Moshe, Moshe” — language of affection, language of urgency.
Custom
Chazal read the doubled call as an expression of divine affection and of the urgency of the moment.