Deuteronomy 2:14-15

2:14 Now the length of time it took for us to go from Kadesh Barnea to the crossing of Wadi Zered was thirty-eight years, time for all the military men of that generation to die, just as the Lord had vowed to them. 2:15 Indeed, it was the very hand of the Lord that eliminated them from within the camp until they were all gone.