וַיְהִ֣י ׀ כְּמֵשִׁ֣יב יָד֗וֹ וְהִנֵּה֙ יָצָ֣א אָחִ֔יו וַתֹּ֕אמֶר מַה־פָּרַ֖צְתָּ עָלֶ֣יךָ פָּ֑רֶץ וַיִּקְרָ֥א שְׁמ֖וֹ פָּֽרֶץ׃
And it came to pass, as he drew back his hand, that, behold his brother came out; and she said: ‘Wherefore hast thou made a breach for thyself?’ Therefore his name was called Perez.
Read halakhic rulings (Jewish law) on Genesis 38:29: and classical halakhic sources.