Commentary for Genesis 31:42

ופחד יצחק AND THE DREAD OF ISAAC — He did not like to say “God of Isaac” because God does not associate His name with the righteous whilst they are alive. And although He (God) said, when he (Jacob) was departing from Beer-Sheba, (Genesis 28:13) “I am the Lord, the God of Abraham thy father and the God of Isaac”, this was because his (Isaac’s) eyes were dim and he might therefore be regarded as dead (Midrash Tanchuma, Toldot 7) — Jacob, however, feared to say “God of Isaac” and said “the Dread”.

AND THE FEAR OF ISAAC HAD BEEN ON MY SIDE. “He did not want to say “G-d of Isaac” because G-d does not associate His name with the righteous during their lifetime. Although G-d said to Jacob when he was departing from the Land of Israel, I am the Eternal, the G-d of Abraham thy father and the G-d of Isaac,²³¹Above, 28:13. this was because Isaac’s eyes were dim, and he might therefore be regarded as dead. Jacob, however, feared to say so, [and instead said, ‘the Fear of Isaac’].” Thus the words of Rashi. It is also the opinion of Onkelos that pachad Yitzchak means “his G-d,” for he translated it as: “He Whom Isaac fears.”
And Rabbi Abraham ibn Ezra said: “Isaac’s fear of G-d helped me, for the merit of the father helps the son. And Jacob swore ‘bepachad’ of his father Isaac,²³²Further, Verse 53. — by Him Whom Isaac fears.” Ibn Ezra’s explanations of the same expression are thus not alike. Ibn Ezra further wrote,²³²Further, Verse 53. “And there are some who say²³³Found in R’dak. that this ‘fear’ is an allusion to the day of Isaac’s Binding.” This is not far fetched.
By way of the Truth [namely, the mystic lore of the Cabala] the language fits its plain meaning and intent, that is, it refers to the attribute of Justice on high.²³⁴See Ramban above, 9:12. Based on this, Scripture says: Afterward shall the children of Israel return, and seek the Eternal their G-d, and David their king; and shall come trembling unto the Eternal and to His goodness in the end of days.²³⁵Hosea 3:5. The verse is stating that they will seek the Merciful One and the attribute of Justice on earth, and bring the Fear of Isaac to G-d and His goodness mentioned.

שלחתני, and not with joy and songs.