פירוש על ברכות 68:30

I CONSIDER IMPUDENT ONE WHO PRAYS IN A FIELD. See Artscroll note 41. And if you ask: but it is written that Yitzchok went out to pray in the field (Braishis 24). Certainly it would be logical that we could follow the behavior of our father Yitzchok, who actually initiated the Minchoh prayer at that time. We can answer: that there the verse is speaking about Mt. Moriah the eventual Temple Mount, as we say in P’sochim perek Ho’eeshoh (88a) in reference to the Temple Mount being referred to as a mountain, the Gemara says not like Yitzchok who called it a field etc., we see that our Sages knew by means of tradition that the field discussed in the verse is Mt. Moriah. The Temple Mount is an area designated for prayer and as such it is no contradiction to our Gemara which is speaking of praying in a field that is not designated for prayer.
Tosfos suggests a second approach to reconcile the two Gemaros. Alternatively, we can answer that the valley of fields mentioned here is speaking about a valley where it is common for people to pass by and is used by road travelers. Because people travel there, it is difficult to concentrate while praying. It is arrogant for one to pray there, because he seems to be saying that I am capable of praying properly even in a place where there are distractions. On the Temple Mount there were no distractions when Yitzchok prayed there. We cannot learn from Yitzchok’s behavior that it is permitted to pray in an area where there are likely to be distractions.

Where people are constantly passing. One should pray in a secluded spot.