Deuteronomy 34:8

And the children of Israel wept for Moses in the plains of
Moab thirty days
According both to Josephus ^F14 and the Samaritan Chronicle ^F15, they cried and wept in a very vehement manner, when he signified to them his approaching death, and took his leave of them; and when he was dead they mourned for him, in a public manner, the space of time here mentioned, the time of mourning for his brother Aaron, ( Numbers 20:29 ) ;

so the days of weeping [and] mourning for Moses were ended;
on the eighth of Nisan or March, as says the Targum of Jonathan, and on the "ninth" they prepared their vessels and their cattle for a march, and on the tenth passed over Jordan, and on the "sixteenth" the manna ceased, according to the said paraphrase.