SHalom!
I study Mishnah Berachot with a Chavruta and we try to ask questions and come up with answers regarding the Mishnah. We cannot understand Rabbi Yehudah's rationale in Mishnah Berachot 4:1. Can you suggest his rationale why Musaf must be prayed before 7 hours?
Bivracha!
Howard Jackson & David Josephs
Howard Jackson, London, UK
As you will have seen from the current Mishnayos that you are learning, the times of all the Tefilos follow the times that the equivalent Korbanos were brought in the Beis-Hamikdash.
Based on that premise, we can solve your problem with a Tosfos on 28a DH 've'Shel'. The Gemara in Pesachim cited by this Tosfos informs us that the Musaf-offering was brought in the sixth hour (from midday) and the Bazichin (the Avodah that followed it), in the seventh. In other words, the Kohanim in the Beis-Hamikdash brought the Musaf between midday and one hour after midday. So that is the end time for Tefilas Musaf according to Rebbi Yehudah.
Incidentally, even Rebbi Yehudah agrees that Bedi'eved, one can Daven Musaf the whole day.
Eliezer Chrysler