Dora Bas Rivka Silver O'H
Amen & Amen
Fortunate is the person who shows proper concern for the sick, says David. Such a person's assistance can reassure the patient of G-d's care. As he helps keep the patient alive, G-d will keep the caregiver alive. He will be an example in the eyes of others and G-d will fortify the patient on his behalf.
David (the patient) had asked G-d to be kind and heal him of the pains he earned through his sins. Gus enemies are standing by, just waiting for him to die. If one of those hypocrites comes to visit him, it's not to wish him well, but to see how close David is to death and laugh about it. He gathers information and shares it with David's other foes, so they can all plot against him.
These enemies say that David is getting what he deserves for his sins, when really they just resent him for foiling their evil schemes. Especially painful are former allies who have turned against him. If G-d would desire it and grant David the strength to do so, David says he would teach those traitors a lesson. David will know that he has pleased G-d when he recovers, since his enemies will then be unable to gloat over his demise.
David is a person of faith, but he stumbled, so G-d "propped him up." David prays that he will continue to have the strength to "stand on his own." He praises G-d from this world to the end of time (and beyond).
David concludes by saying "amein v'amein," i.e., amen in this world and amen in the next. ("Amen" is an expression of emunah - belief - as in "ani maamin," I believe.")
While Tehillim (Psalms) is a single Biblical book with continuous numbering, it is subdivided into five thematic "books." This Psalm completes the first "book," which focused heavily on David thanking G-d for His kindness and on his illness, which David attributed to his sins.