Reference for Shabbat 238:2
אמר רבא ואיתימא ר' יהושע בן לוי אפי' יחיד המתפלל בע"ש צריך לומר ויכולו דאמר רב המנונא כל המתפלל בע"ש ואומר ויכולו מעלה עליו הכתוב כאילו נעשה שותף להקב"ה במעשה בראשית שנאמר ויכולו אל תקרי ויכולו אלא ויכלו אמר רבי אלעזר מניין שהדיבור כמעשה שנאמר (תהלים לג, ו) בדבר ה' שמים נעשו
for R. Hamnuna said: He who prays on the eve of the Sabbath and recites 'and [the heaven and the earth] were finished,' the Writ treats of him as though he had become a partner with the Holy One, blessed be He, in the Creation, for it is said, Wa-yekullu [and they were finished]; read not wa-yekullu but wa-yekallu [and they finished].<span class="x" onmousemove="('comment',' 'They' referring to God and to him who praises God for the Creation. ');"><sup>4</sup></span> R. Eleazar said: How do we know that speech is like action? Because it is said, By the word of the Lord were the heavens made.<span class="x" onmousemove="('comment',' Ps. XXXIII, 6. ');"><sup>5</sup></span> R. Hisda said in Mar 'Ukba's name: He who prays on the eve of the Sabbath and recites and [the heaven and the earth] were finished, the two ministering angels who accompany man place their hands on his head and say to him, and thine iniquity is taken away, and thy sin purged.<span class="x" onmousemove="('comment',' Isa. VI, 7. ');"><sup>6</sup></span>