The James Strong and McClintock Encyclopedia says a soul is "that vital, immaterial, active substance, or principles in man whereby he perceives, remembers, reasons, and wills."The International Standard Bible Encyclopedia says a soul is a “living being, life, self, person, desire, appetites, emotions and passions.
In light of understanding what "soul" means, let's review what the Apostle John said about the matter. 3 John 1:2 says, "Beloved, I wish above all things that you may prosper and be in health, even as your soul prospers," I wonder if John is saying to us, O.K., I know you want to prosper financially but for your soul's sake I want you to prosper only according to your ability to be prosperous toward God. Maybe, he had Luke 12:20-21 in mind when he wrote the passage. Perhaps he had a flashback, recalling the parable of the rich man whose land produced an abundant crop and upon seeing the abundance the man said to his soul "thou hast much goods laid up for many years; take thine ease, eat, drink, and be merry." But God said unto him, Thou fool, this night thy soul shall be required of thee: then whose shall those things be, which thou hast provided? So is he that layeth up treasure for himself, and is not rich toward God.
John appears to agree with Jesus, that Christians shouldn't be financially prosperous but spiritually poor.We see in scripture some were rich toward God so He made them rich on earth.
Do you delight to do God's will like David? David said, I delight to do your will o' Lord. He also said He loved the word of God, he said it was sweet, sweeter than honey and the honeycomb (Psalms 19:10). The word of God was better to him than fine gold (Psalm 19:10, Psalm 119:122).
Job was the richest man of the East but scripture also says, He shunned evil like no other (Job 1:1-12)
Abraham was also blessed with riches, some say it was simply based on his faith but God said, Abrahm would inherit the promises because he would teach his household to obey him (Genesis 18:18-19).
On the other hand we have people like Achan who coveted and stole clothes and jewelry from property seized in war (Joshua 7:1-26), Gehazi lied to get clothes and money (2 Kings 5:21-27), For fame and money Balaam taught Balak how to get God to curse Israel (Numbers 22:17, Jude 1:11) Judas betrayed Christ for money(Matthew 27:3-5) and Ananias and Sapphire lied to God and the apostles regarding property and money (Acts 5:1-11). So unlike David, instead of finding delight in God they found delight in possessing and owning things and impressing people.
Soul prosperity will occur when we "seek first the kingdom of God, and his righteousness" then the things we want shall be added unto us. They will be added to us, we won't have to lie to get them, nor will we have to steal, deceive or go bankrupt to get them.