Brachos 3:6-4:1

Brachos 3:6

The following people must immerse in a mikvah: a zav (a man who had a particular type of emission) who subsequently had a seminal emission; a niddah (a menstruating woman) who expelled semen from a prior sexual act; a woman who had sexual relations and then saw that she was menstruating. (The reason for all three is Ezra’s enactment regarding baal keri, which is not observed today – see 3:4. In each of these cases, the person must immerse even though they will remain impure from some other factor.) Rabbi Yehuda does not require them to immerse.

Brachos 4:1

The morning Shemoneh Esrei may be recited until noon (meaning the midpoint of the daylight hours, not 12:00); Rabbi Yehuda says through the fourth hour of the day (which is one-third of the day). The afternoon Shemoneh Esrei may be recited until evening; Rabbi Yehuda says until plag hamincha (the midpoint of the mincha period). There is no set time for the night Shemoneh Esrei and musaf (the additional service on Shabbos, Festivals and Rosh Chodesh) may be recited all day; Rabbi Yehuda says that musaf may be recited until the seventh hour of the day (i.e., an hour later than the morning service).