וַיִּקְרָ֨א אַבְרָהָ֜ם אֶֽת־שֶׁם־בְּנ֧וֹ הַנּֽוֹלַד־ל֛וֹ אֲשֶׁר־יָלְדָה־לּ֥וֹ שָׂרָ֖ה יִצְחָֽק׃
And Abraham called the name of his son that was born unto him, whom Sarah bore to him, Isaac.
Read kabbalistic (mystical) interpretation of Genesis 21:3: and classical mystical sources.