Targum zu Dewarim 34:8

And the children of Israel wept for Mosheh in the plains of Moab thirty days; and the days of weeping in the mourning for Mosheh were completed on the eighth of the month of Nisan. And on the ninth of Nisan the people of Beth Israel prepared their vessels and set their cattle in order, and passed over the Jordan on the tenth of Nisan. And the manna ceased for them on the sixteenth of Nisan. They found manna to eat thirty_seven days after the death of Mosheh, for the sake of his righteousness.

And the children of Israel wept for Mosheh in the plains of Moab thirty days; and so were fulfilled the days of weeping in mourning for Mosheh.