Reference for Genesis 15:10

וַיִּֽקַּֽח־ל֣וֹ אֶת־כָּל־אֵ֗לֶּה וַיְבַתֵּ֤ר אֹתָם֙ בַּתָּ֔וֶךְ וַיִּתֵּ֥ן אִישׁ־בִּתְר֖וֹ לִקְרַ֣את רֵעֵ֑הוּ וְאֶת־הַצִפֹּ֖ר לֹ֥א בָתָֽר׃

And he took him all these, and divided them in the midst, and laid each half over against the other; but the birds divided he not.