וּמְעוֹנֹתַ֖י הוֹלִ֣יד אֶת־עָפְרָ֑ה וּשְׂרָיָ֗ה הוֹלִ֤יד אֶת־יוֹאָב֙ אֲבִי֙ גֵּ֣יא חֲרָשִׁ֔ים כִּ֥י חֲרָשִׁ֖ים הָיֽוּ׃ (פ)
און מְעוֹנוֹתַי האָט געבאָרן עָפֿרָהן; און שׂרָיָה האָט געבאָרן יוֹאָבֿ דעם פֿאָטער פֿון גֵיא-חַרָשים; װאָרום זײ זײַנען געװען מײַנסטערס.
Rashi
And Seraiah begot Joab, the leader of Gei Harashim Joab was the leader of a valley in which there were craftsmen. Now why do I call it the Valley of Craftsmen? Because they were craftsmen; i. e., those who dwelt in the Valley of the Craftsmen were craftsmen, and the valley was named after them.