וַיַּ֣רְא יַעֲקֹ֔ב כִּ֥י יֶשׁ־שֶׁ֖בֶר בְּמִצְרָ֑יִם וַיֹּ֤אמֶר יַעֲקֹב֙ לְבָנָ֔יו לָ֖מָּה תִּתְרָאֽוּ׃
Now Jacob saw that there was corn in Egypt, and Jacob said unto his sons: ‘Why do ye look one upon another?’
Read halakhic rulings (Jewish law) on Genesis 42:1: and classical halakhic sources.