וַיֹּ֕אמֶר אָנֹכִ֛י אֲשַׁלַּ֥ח גְּדִֽי־עִזִּ֖ים מִן־הַצֹּ֑אן וַתֹּ֕אמֶר אִם־תִּתֵּ֥ן עֵרָב֖וֹן עַ֥ד שָׁלְחֶֽךָ׃
And he said: ‘I will send thee a kid of the goats from the flock.’ And she said: ‘Wilt thou give me a pledge, till thou send it?’
Read midrashic interpretation of Genesis 38:17: and classical rabbinic exegesis.