If I do not remember thee,.... In prayer, in discourse, in conversation; this is the same as before, to forget, repeated for the confirmation of it;let my tongue cleave to the roof of my mouth; as is the case of a person in a fever, or in a violent thirst, which is to be in great distress, Ps 18:6; the sense is, let me have no use of my tongue; let me be dumb and speechless, and never sing a song or speak a word more, should I be so forgetful of the deplorable state of Jerusalem as to sing songs at such a season, and in an enemy's country;if I prefer not Jerusalem above my chief joy; meaning not God his exceeding joy, Ps 43:4; as his Creator, preserver, and benefactor, and much less as his covenant God and Father; as having loved him with an everlasting love; as the God of all grace unto him, and as his portion and exceeding great reward: nor Christ, the object of joy unspeakable and full of glory; joy in the greatness, glory, and fulness of his person; in the blessings and promises of his grace; in what he has done and suffered; as risen, ascended, exalted, and who will come a second time: nor the joy of the Holy Ghost in a way of believing, and in hope of the glory of God; but all worldly joy, or matter of it; and this not in things sinful, nor merely such as worldlings have in the increase of their substance; but a lawful joy, such as in the health, happiness, and prosperity of a man's family, wife, and children, and his own; which is the greatest outward joy a man can have; and yet the church of God and interest of Christ are preferred by a good man to these; see 1Sa 4:19; which appears when all a man has that is matter of joy is sacrificed for the public good and interest of religion; when he can take no comfort in any outward enjoyment because of the sad case of Zion, Mal 2:3; when joy for its good is uppermost, and is first in his thoughts and words; when this is the "head" or "beginning" of his joy, as it may be rendered.
So Pindar calls the chief, principal, and greatest part of joy, aglaiav arca, the beginning of joy, the top and perfection of it. ytxmv var "caput laetitiae meae", Musculus, Junius & Tremellius, Piscator, Gejerus.
Pythia, Ode 1. v.