הלכה על ראש השנה 31:5

On weekdays, one must not interrupt between Ga’al Yisrael and the Amida for any davar she-bikdusha, for adjoining redemption to prayer helps save people from distress. However, on Shabbat, which is not considered a day of distress, there is less of a necessity to adjoin redemption to prayer, and according to most poskim one may interrupt to respond to devarim she-bikdusha. On festivals, which are days of judgment (on Sukkot, we are judged regarding water, on Pesaḥ regarding the harvest, and on Shavuot regarding tree fruits – see RH 16a), one may not interrupt between redemption and prayer (SA 66:9; Rema 111:1; Peninei Halakha: Prayer, ch. 16 n. 7).

It is from the roots of this commandment that God, blessed be He, commanded us the constant commandment of the bread, on account that through it a man lives; and as a result, [the commandment] is needed by him for blessing to always be found in [his bread]. And from our involvement in it to fulfill the commandment of God, may He be blessed, the [Divine] will and blessing will descend upon us, and that which is similar to it will be blessed. And according to each and every matter upon which he places the conglomeration of his focus, his thoughts and his activities by way of a commandment - according to them, a similar blessing will emerge upon him. And so I have found [in] Ramban (Ramban on Exodus 25:24). And [it] is like the matter that they, may their memory be blessed, said (Rosh HaShanah 16:1), "Bring the omer (barley offering) in front of Me at Pesach, in order that the grain in the fields will be blessed for you; pour the water in front of Me on the Festival (Sukkot), in order that the rains of blessing will be blessed for you in the coming year; blow the ram's horn (shofar) in front of Me, in order to remember the binding of Yitschak." And they said about this very same bread (Megillah 26b) that because it is an accessory of the commandment, and through it the will of God is done, blessing would cling to it more. And [so] each one of the priests who had from it coming to him would be twice as satiated.