Numbers 13:25

And they returned from searching the land after forty days.
] The Targum of Jonathan adds, on the eighth day of the month Ab, which answers to part of July and part of August; so that this must be towards the latter end of July: some Jewish writers ^F11 say it was the ninth of Ab; hence the tradition, that it was decreed on the ninth of Ab concerning their fathers, that they should not enter into the land {l}.