Limit to Testing

 I have heard these words many times " G-d never gives a person a test greater than what he can deal with"

What is the source for this claim? It is a widespread Christian belief

Bereishis Rabbah (34:02) A potter does not test defective vessels, because he cannot give them a single blow without breaking them. Similarly, the Holy One, blessed be He, does not test the wicked but only the righteous: thus,  The Lord trieth the righteous.’ R. Jose b. R. Hanina said: When a flax worker knows that his flax is of good quality, the more he beats it the more it improves and the more it glistens; but if it is of inferior quality, he cannot give it one knock but it splits. Similarly, the Lord does not test the wicked but only the righteous, as it says: ' The Lord trieth the righteous. R. Eleazar said: When a man possesses two cows, one strong and the other feeble, upon which does he put the yoke? Surely upon the strong one. Similarly, the Lord tests none but the righteous; hence, ' The Lord trieth the righteous.

 Bereishis Rabbah (56:11)AND THE ANGEL OF THE LORD CALLED UNTO ABRAHAM A SECOND TIME OUT OF HEAVEN, AND SAID: BY MYSELF HAVE I SWORN What was the need of this oath? He had begged Him: Swear to me not to try me again henceforth, nor my son Isaac. R. Levi in the name of R. Hama b. R. Hanina gave another reason for this oath: He had begged: ' Swear to me not to test me again henceforth. This may be likened to a king who was married to a noble lady. She gave birth to her first son by him, and he divorced her; a second, and he divorced her; a third, and he divorced her. When she had given birth to a tenth son by him, they all assembled and demanded of him: ‘Swear to us not to divorce our mother again.’ Similarly, when Abraham had been tried for the tenth time, he said to Him: Swear to me not to test me again. R. Hanan commented: BECAUSE THOU HAST DONE THIS THING it was the tenth trial, yet you say, BECAUSE THOU HAST DONE THIS THING! The fact, however, is that this was the last trial, which was as weighty as all the rest together, and had he not submitted to it, all would have been lost.