At the end of forty days they returned from spying out the land: The pronoun they refers to the twelve spies, which translators may need to make explicit in the same way as in verse 21 (see the comments there). The verb returned marks the conceptual closure of returning from a mission and spying out forms an inclusio with forms of the same Hebrew verb in verses 2, 16-17, and 21.

Quoted with permission from de Regt, Lénart J. and Wendland, Ernst R. A Handbook on Numbers. (UBS Helps for Translators). Miami: UBS, 2016. For this and other handbooks for translators see here .