וַיִּשְׁמַ֣ע רְאוּבֵ֔ן וַיַּצִּלֵ֖הוּ מִיָּדָ֑ם וַיֹּ֕אמֶר לֹ֥א נַכֶּ֖נּוּ נָֽפֶשׁ׃
And Reuben heard it, and delivered him out of their hand; and said: ‘Let us not take his life.’
Read kabbalistic (mystical) interpretation of Genesis 37:21: and classical mystical sources.