וַיָּבֹ֥אוּ אֶל־נֹ֖חַ אֶל־הַתֵּבָ֑ה שְׁנַ֤יִם שְׁנַ֙יִם֙ מִכָּל־הַבָּשָׂ֔ר אֲשֶׁר־בּ֖וֹ ר֥וּחַ חַיִּֽים׃
And they went in unto Noah into the ark, two and two of all flesh wherein is the breath of life.
Read halakhic rulings (Jewish law) on Genesis 7:15: and classical halakhic sources.