say of my soul - that is, “of me” (compare Psa 25:3). This use of “soul” is common; perhaps it arose from regarding the soul as man’s chief part.
no help ... in God - rejected by Him. This is the bitterest reproach for a pious man, and denotes a spirit of malignant triumph.
Selah - This word is of very obscure meaning. It probably denotes rest or pause, both as to the music and singing, intimating something emphatic in the sentiment (compare Psa 9:16).