Two Possibilities Regarding Joshua’s Fate

From the dual pronoun in the verb “they both set out” (fa-nṭalaqā) which follows from what came before, and from “they both boarded” (rakibā), it appears that Joshua, who had accompanied Moses to the “junction of the two seas” (majmaʿ al-baḥrayn), separated from them and did not board the ship with them. According to some accounts, Moses sent Joshua back to the Children of Israel from there.(233)

Joshua was with them; however, since the central figures of the story were Moses and al-Khiḍr, and Joshua had no role, God used the dual pronoun and did not say “they (plural) set out until when they boarded.”