Midrash su Salmi 81:1

... Another explanation. Why does the verse (Psalms 81:2) mention Yaakov and not all of the forefathers? Our rabbis taught: a man is measured with the measure by which he measures, as it says “In that measure (b’saseah), when they sent them out, it strove with it…” (Isaiah 27:8) A seah with a seah. I only know seah, from where do I learn tirkav and a half tirkav, kab and a half kav, rovah and a half rovah, a tuman and an uchlah? Scripture says “For every victory shout (s’on soein) sounds with clamor…” (Isaiah 9:4) Here there are many measures. I only know about something which comes by measure, from where do I learn little bits that add up to a large amount? Scripture says “…adding one to another to find out the account.” (Ecclesiastes 7:27) This is like a king who had three people that loved him, and sought to build himself a palace. He brought the first one and said to him: I want to build a palace for myself. His love replied to him: I recall that it was a mountain in the beginning. He called to the second love and said to him: I want to build a palace for myself. He replied: I recall that it was a field in the beginning. He called to the third love and said: I want to build a palace for myself. He replied: I recall that it was a palace in the beginning. He said to him: by your life! I will build that palace and call it by your name. So too Avraham, Yitzchak and Yaakov were lovers of the Holy One. Avraham called the Holy Temple ‘mountain,’ as it says “On the mountain, the Lord will be seen.” (Genesis 22:14) Yitzchak called it field, as it says “…the fragrance of my son is like the fragrance of a field…” (Genesis 27:27) Yaakov called it ‘house’ even before it was built, as it says “This is none other than the house of God…” (Genesis 28:17) The Holy One said to him: by your life! You called it a house before it was built and I will call it by your name, as it says “Come, let us go up to the Lord's mount, to the house of the God of Jacob…” (Isaiah 2:3) So too Jeremiah said “So said the Lord: Behold I am returning the captivity of the tents of Jacob…” (Jeremiah 30:18) So too Asaf decorated his words and only recalled the God of Yaakov with a trumpet blast, as it says “…sound the shofar to the God of Jacob.” (Psalms 81:2)