The extension of jah's hand - herb - is the very salvation by which he makes us high. The psalmist prays in accordance with jah's will and provision rather than seeking alternatives.
A prayer specifically for the needy.
A prayer specifically for those in pain.
An educated prayer invoking specific spiritual aid...
...with expectation and a song of praise
for the healing character of jah is already extended
via his hand.
Overstand the purpose of herb; the hand of jah: It saves the needy and in pain by making us high. "Make me high" is the explicit request of the Psalmist who resolves with praise for the hand which delivers the required spiritual solution.
Yes, Cannabis does exactly what jah made it to do. It quiets the mind as it lifts the spirit...
Again, the psalmist instructs what followed by how:
Are you needy and in pain?
Jah offers his hand to help you and give you relief.
Another psalmist, needy and in pain, praises the hand which lifts us:
Jason Mraz-You make me high
Something got you down? Let jah's beautiful hand make you high... Pray about it.
Love one another.