Talmud for Shabbat 268:6
תניא כוותיה דרבא מרחיצין הקטן בין לפני מילה בין לאחר מילה ביום ראשון כדרכו וביום השלישי שחל להיות בשבת מזלפין עליו ביד ר"א בן עזריה אומר מרחיצין את הקטן ביום השלישי שחל להיות בשבת ואע"פ שאין ראיה לדבר זכר לדבר שנאמר ויהי ביום השלישי בהיותם כואבים
Rather said Raba, He teaches thus: WE MAY BATHE THE INFANT BOTH BEFORE AND AFTER CIRCUMCISION on the first day in the normal manner; but on the third day which falls on the Sabbath, WE SPRINKLE [WARM WATER] OVER HIM BY HAND BUT NOT WITH A VESSEL. R. ELEAZAR B. AZARIAH SAID: WE MAY BATHE AN INFANT ON THE THIRD DAY WHICH FALLS ON THE SABBATH, BECAUSE IT IS SAID, AND IT CAME TO PASS ON THE THIRD DAY, WHEN THEY WERE SORE. It was taught in accordance with Raba: We may bathe the infant before and after the circumcision on the first day in the normal manner, but on the third day which falls on the Sabbath we besprinkle him by hand. R. Eleazar b. 'Azariah said: We may bathe an infant on the third day which falls on the Sabbath, and though there is no proof, there is an allusion thereto, for it is said, 'And it came to pass on the third day, when they were sore'. And when they sprinkle, they sprinkle neither with a glass nor with a dish nor with a vessel, but only by hand — this agrees with the first Tanna. Why [does he say,] though there is no proof, there is an allusion thereto?<span class="x" onmousemove="('comment',' Surely this is a proof that the third day is dangerous. ');"><sup>5</sup></span>