John Calvin Commentary Psalms 103:1

"Bless Jehovah, O my soul; And all that is within me, [bless] his holy name." — Psalms 103:1 (ASV)

Bless Jehovah, O my soul! The prophet, by stirring himself up to gratitude, gives by his own example a lesson to everyone about the duty incumbent on them. And doubtless our slothfulness in this matter needs continual incitement. If even the prophet, who was inflamed with a more intense and fervent zeal than other men, was not free from this malady—of which his earnestness in stimulating himself is a plain confession—how much more necessary is it for us, who have abundant experience of our own torpor, to apply the same means for our own awakening?

The Holy Spirit, speaking through him, indirectly rebukes us for not being more diligent in praising God. At the same time, the Spirit points out the remedy: that everyone should look within themselves and correct their own sluggishness.

Not content with calling upon his soul (by which he unquestionably means the seat of the understanding and affections) to bless God, the prophet expressly adds his inward parts, addressing, so to speak, his own mind and heart, and all the faculties of both. When he speaks to himself in this way, it is as if, removed from the presence of men, he examined himself before God. The repetition makes his language still more emphatic, as if he intended by this to reprove his own slothfulness.