וַתֹּ֤סֶף עוֹד֙ וַתֵּ֣לֶד בֵּ֔ן וַתִּקְרָ֥א אֶת־שְׁמ֖וֹ שֵׁלָ֑ה וְהָיָ֥ה בִכְזִ֖יב בְּלִדְתָּ֥הּ אֹתֽוֹ׃
And she yet again bore a son, and called his name Shelah; and he was at Chezib, when she bore him.
Targum Jonathan on Genesis
And she added, and bare a son, and called his name Shela, because her husband had forgotten her and was in cessation when she bare him.