Crying in Vain and Endless Trouble
Talmud Bavli, Suttah Tractate, 34, 71 - 35-72
“That night all the members of the community raised their voices and wept aloud” [Numbers 14:1*], Rabbah said, Rabbi Yohanan said:
That day (in the evening) it was Tisha B’Av, the Holy One Blessed Be He said weep your crying in vain, and I will set for you endless trouble, and all the community said to stone them with stones and it is written:
“The Lord God was seen in the tent of the congregation”. Rabbi Haya Bar Abba said: this teaches us that they took stones and threw them upwards.
*The connection with the verse is the crying of the Children of Israel complaining following the report of the spies regarding the Land of Israel and ask to return to Israel.