Midrash for Sanhedrin 79:7
אחד אומר בשתי שעות ואחד אומר בשלש שעות עדותן קיימת אחד אומר בשלש ואחד אומר בחמש עדותן בטילה
IF ONE [WITNESS] TESTIFIES, '[IT HAPPENED] ON THE SECOND OF THE MONTH,' AND THE OTHER, 'ON THE THIRD OF THE MONTH:' THEIR EVIDENCE IS VALID, FOR ONE MAY HAVE BEEN AWARE OF THE INTERCALATION OF THE MONTH AND THE OTHER MAY NOT HAVE BEEN AWARE OF IT.<span class="x" onmousemove="('comment',' I.e., one knew that the previous month had consisted of thirty days whilst the other thought that it had consisted only of twenty-nine days provided they agree as to the day of the week. Cf. Kesef Mishneh, on Yad'Eduth II, 4, and Tosaf. 41b s.v. [H]. ');"><sup>12</sup></span> IF, HOWEVER, ONE SAYS, 'ON THE THIRD,' AND THE OTHER, 'ON THE FIFTH, THEIR EVIDENCE IS INVALID. SIMILARLY, IF ONE TESTIFIES, 'DURING THE SECOND HOUR [OF THE DAY]'<span class="x" onmousemove="('comment',' The length of the day was counted from sunrise to sunset, and having regard to the variation of that period, an hour lasted anywhere between 49 and 71 minutes. ');"><sup>13</sup></span>