Before we get too comfortable putting ourselves in this man's shoes we should realize that this man is not being persecuted because he is a common run of the mill believer, he is an uncommon public promoter of the faith effectively making a difference for the Lord helping to establish a righteous nation in the midst of great opposition. Most likely this is King David, a man perhaps like no other. From that standpoint should the similarities to our situations be considered.
Like with so many of these psalms, with some careful interpretation as to the haste mentioned here and the removal of kjv@Psalms:31:10 these could almost be our Lord's words. Jesus did quote "Into Thine hands...". That David could perceive in his own experiences much of what his Seed would in His is astounding. It would be interesting to know what particular experience of his David is speaking of. Sometimes it feels as if we share this experience in our lives as well.
Rejoicing here is connected directly to praise. Rejoicing makes for praise and praise makes for rejoicing. Praise comes with knowledge of who God is and what He does. Praise comes with deepening reverence for the size and scope and breadth; it is from the lips. Rejoicing comes with hope; it comes from the heart.
As I read it, it is not that the righteous don't have troubles and afflictions, it is that the Lord delivers us out of them. Trust, fear, turning from evil and keeping our tongue/lips, seeking peace and His face, tasting, praising and joining together in praise; these are the things that we should be doing through it all.
The picture here is of someone coming to the cause of the poor and needy, the quiet ones of the land, ones under the heavy hand of these evil enemies. This someone stands in the way of the enemy and is thus treated falsely being accused of things that he knew not. Snares are laid in his path. When the enemy is sick, he prays for them as he would a friend. When they are strong he prays for the Lord to arise to confound and scatter their purposes for righteousness sake. We would be well advised to be this type of person being assured that our God is all of this and more.
Compare and contrast. If the author were to tell us all the good things of God no doubt that would be interesting but, not as informative and ground breaking as the same thing contrasted light to dark. We witness more about Him and more about the wicked. It is like a painting verses a charcoal sketch.
The case against atheism can be made that without a reverent image of God that those individuals with wicked tendencies are emboldened to commit much more serious forms wickedness. I write this three days after a mass murder was committed by a lone gunman at our local movie theater. The fear of God would have major benefit even in a secular society.
Trust, Delight, Commit, Trust, Rest, Cease from anger, Shew mercy, Giveth, Speak Wisdom, Talk Judgement, as opposed to Plot, Gnash, Draw bow, Cast down poor/needy, Slay upright, Borrow and not pay back, Watch with intent of slaying righteous. Contrasts create a fairly vivid picture.
We see that is is totally possible to be two things at once; to be perceived and pursued as following the "thing that is good" and to be deeply disquieted by ones own sin. The weight of such is a heavier burden on the soul than the consciousness of God's reproof might otherwise be. And yet we see that there still is hope, petition can be prayed, the required repentance still can be made for those honest enough and willing.
I have felt at times that it was best to keep my silence/bridle my tongue before the enemies of God that I not myself display to them a more sinful side of myself that might spill out unintended. By this I intend good but may well carry it too far as if I to be outright deaf and mute to the calling of God. The psalmist here in similar ill is prescribed a dosage of knowing his end, his frailty and the measurement of his days.