Bava Metsia 5

עוד היא בשלא אמר יזכו לי בד' אמות שלי. והתנינן קרוב לה מגורשת קרוב לו אינה מגורשת מחצה למחצה מגורשת ואינה מגורשת. חזקיה אמר בשכר הליבלר היא מתניתא. התיבון והכתיב ואני בעוניי הכינותי וגו' והיכי אם בנתונין בתוך ידו עשיר הוא אי בשאינן נתונין לתוך ידו יש אדם מקדיש דבר שאינו שלו הוי אומר בנתונין בתוך ד' אמות שלו.

R. Hanina says: The sun must have gone down and the moon have commenced to rise. In effect R. Samuel says: The moon cannot shine as long as the sun still lightens, neither can the moon shine after the sun has darted his (morning) beams. R. Samuel bar-Hiya, in the name of R. Hanina, says: If a man, when the sun has begun to set, descends from the summit of Mount Carmel to bathe in the sea, and re-ascends to partake of the oblations, he has certainly bathed during the daytime. It is, however, only a certainty in the case of one taking cross-roads to shorten the route; but not in the case of one who follows the high road (Strata). What is meant by "the intermediate period "? R. Tanhooma says: It resembles the delay of a drop of blood placed on the edge of a sword, i.e. the time required for the drop of blood to divide and run down on either side of the blade, is equivalent to the period of transition. According to R. Nehemiah, it means the time it would require for a man to run half a mile, after sunset. R. Yosse says: This twilight lasts no longer than the twinkling of an eye, and not even the men of science could measure it. Whilst the R. Yosse and R. Aha were together, the former said to the latter: Does it not seem to you that the passage of this half a mile (twilight) lasts but a second? It is certainly my opinion, said R. Aha. However, R. Hiya does not say so, but each twinkling of an eye, measured by the duration of the passage of half a mile (as R. Nehemiah), is doubtful. R. Mena says : I have made an objection in the presence of R. Aha: Have we not learnt elsewhere, that if an impurity is seen, once during the day and again during the intermediate period, or once in the twilight and again on the morrow, when the certainty exists that the impurity dates partly from this day and partly from the next day, there is a certainty as to the circumstances of the impurity, and the sacrifice is obligatory.