פּירוש אויף מלכים א 3:27

“The king responded: give her the live child, etc.” [3:27]. The king said: give her the live child and the child should not be killed, since this is his mother. The Midrash writes that a Heavenly voice went forth and said: this is his mother. That is to say, that Solomon had judged correctly.⁴Genesis Rabbah, 85.12.

She is his mother. A Divine voice appeared and said, “She is his mother.”²⁶See Rashi in Maseches Makos 23b.