Mishnayos Parah Perek 12 Mishnah 11

ביום והזה בלילה פסול – as it is written (Numbers 19:19): “The pure person shall sprinkle it upon the impure person on the third day and on the seventh day, [thus purifying him by the seventh day],” during the day, but not at night. And there is an analogy made between ritual immersion and sprinkling, as it is written (Numbers 19:18): “[A person who is pure shall take hyssop] dip it in the water, and sprinkle [on the tent and on all the vessels and people who were there,]” just as sprinkling is during the day, even ritually immersion of the hyssop is during the day.

טובל בלילה ומזה ביום – where he delayed his immersion and did not sprinkle on the seventh day, when he does to sprinkle on the eighth or ninth or tenth [days] he is able to advance ritual immersion to sprinkling. But a person who ritually immerses on the seventh according to his precept, he sprinkles first and afterwards ritually immerses, as it is written (Numbers 19:19): “thus purifying by the seventh day,” and afterwards it is written: “He shall then wash his clothes and bathe in water.” (see also Tractate Megillah, Chapter 2, Mishnah 4 – that a person does not ritually immerse in water nor sprinkle other than during the daytime).

משעלה עמוד השחר כשר – that from then onwards it is day, as it is written (Nehemiah 4:15): “And so we worked on, while half were holding lances, from the break of day until the stars appeared,” and it is written there (Nehemiah 4:16): “[I further said to the people at that time: ‘Let every man with his servant lodge in Jerusalem,] that we may use the night to stand guard and the day to work.’” (see also Tractate Berakhot, Chapter 1, Mishnah 1 for the usage of the phrase "עד שיעלה עמוד השחר"/until the crack of dawn).