Reference for Sanhedrin 213:1
אוכל לחמי הגדיל עלי עקב
which did eat of my bread, hath lifted up his heel against me.<span class="x" onmousemove="('comment',' Ibid. XLI, 10. This is understood to refer to Ahitophel, and 'which did eat my bread', as a metaphor for 'who learnt of my teaching'. ');"><sup>1</sup></span> Rab Judah said in Rab's name: One should never [intentionally] bring himself to the test, since David king of Israel did so, and fell. He said unto Him, 'Sovereign of the Universe! Why do we say [in prayer] "The God of Abraham, the God of Isaac, and the God of Jacob," but not the God of David?' He replied, 'They were tried by me, but thou wast not.' Then, replied he, 'Sovereign of the Universe, examine and try me' — as it is written, Examine me, O Lord, and try me.<span class="x" onmousemove="('comment',' Ibid. XXVI, 1. ');"><sup>2</sup></span>