Where is the word “prosperity” in the New Testament?

Here is the short answer: ZERO, NONE, NOT THERE.
So after thinking on that a few moments what does that mean?
That Jesus never taught prosperity? That would be a yes.
That we are not to seek to be prosperous? I would say yes to this as well. In fact Jesus says it is harder for a rich man to get into heaven then a poor one.
Then why would you seek to be prosperous? ………………………………………………
You should not.
So why would you listen to someone that says we should seek to be prosperous? Again you should not.
Seeking to be prosperous is seeking to be a part of the world. For being prosperous will only do you any good in the world. Since the world is temporal and not everlasting why even seek it. All we are required to do is seek enough to get us fed today, that is in the Lord ’s Prayer. This is what Jesus said on the Sermon on the Mount about prosperity:
Matthew 6: 24 No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon. 25 Therefore I say unto you, Take no thought for your life, what ye shall eat, or what ye shall drink; nor yet for your body, what ye shall put on. Is not the life more than meat, and the body than raiment?……………… 31 Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed? 32 (For after all these things do the Gentiles seek:) for your heavenly Father knoweth that ye have need of all these things. 33 But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you. 34 Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof.

Seek first the kingdom of God and His righteousness then he will reward you. Isn’t seeking after prosperity placing that before God? The answer is yes.
Then it is not Biblical to seek out prosperity and any that teach otherwise does not serve God but the world.

Prosperity – The Christian definition

Per Merriam-Webster prosperity is defined as “the condition of being successful or thriving.”
But want does that mean to those that profess to be “Christian?”
What is Christian success? What is thriving as a Christian?”
The best place to start to look for this answer is in Mark. Chapter ten to be exact:
17 As Jesus was starting out on his way to Jerusalem, a man came running up to him, knelt down, and asked, “Good Teacher, what must I do to inherit eternal life?” 18 “Why do you call me good?” Jesus asked. “Only God is truly good. 19 But to answer your question, you know the commandments: ‘You must not murder. You must not commit adultery. You must not steal. You must not testify falsely. You must not cheat anyone. Honor your father and mother.” 20 “Teacher,” the man replied, “I’ve obeyed all these commandments since I was young.” 21 Looking at the man, Jesus felt genuine love for him. “There is still one thing you haven’t done,” he told him. “Go and sell all your possessions and give the money to the poor, and you will have treasure in heaven. Then come, follow me.” 22 At this the man’s face fell, and he went away sad, for he had many possessions. 23 Jesus looked around and said to his disciples, “How hard it is for the rich to enter the Kingdom of God!” 24 This amazed them. But Jesus said again, “Dear children, it is very hard to enter the Kingdom of God. 25 In fact, it is easier for a camel to go through the eye of a needle than for a rich person to enter the Kingdom of God!”
Here is the first and most important fact about Christian prosperity. This young man was rich and full of earthly prosperity and he even was a loyal servant to God and for this Jesus looked upon him with love. But Jesus knew his heart and knew that the world was more important to him than God. He was a true “lukewarm.” So Jesus offered him Christian prosperity, but to gain it he must surrender all his earthly prosperity.
Jesus makes it clear in these verses. That those with earthly prosperity will have a hard time gaining access into heaven and if they do their reward which is true Christian prosperity will be lacking.
So any that teach worldly prosperity are turning you away from Jesus not toward Him, and so are naked and poor. (Revelation 3: 15 “I know all the things you do, that you are neither hot nor cold. I wish that you were one or the other! 16 But since you are like lukewarm water, neither hot nor cold, I will spit you out of my mouth! 17 You say, ‘I am rich. I have everything I want. I don’t need a thing!’ And you don’t realize that you are wretched and miserable and poor and blind and naked.”)
Mark 10:26 The disciples were astounded. “Then who in the world can be saved?” they asked. 27 Jesus looked at them intently and said, “Humanly speaking, it is impossible. But not with God. Everything is possible with God.” 28 Then Peter began to speak up. “We’ve given up everything to follow you,” he said. 29 “Yes,” Jesus replied, “and I assure you that everyone who has given up house or brothers or sisters or mother or father or children or property, for my sake and for the Good News, 30 will receive now in return a hundred times as many houses, brothers, sisters, mothers, children, and property—along with persecution. And in the world to come that person will have eternal life. 31 But many who are the greatest now will be least important then, and those who seem least important now will be the greatest then.”
Here in these verses above Jesus makes it clear what true Christian prosperity looks like. He also makes it clear that it is not of this earth, and what is of this earth will persecute them. Those that are great in the world will become those that are the least notable in the eternal life that is to come, while those that are poor and the least same become great for billions upon billions of years. As I have stressed before, this earthly existence in which people seek that which is not Christian prosperity have at the most 100 years, and not even that amount to fully enjoy their earthly reward. While our eternal reward will last 1000000000000000000000000000000000000000000000000000000000000000000000 of years, which is greater?
This is what Jesus says about material needs:
Matthew 6:24-34New Living Translation (NLT)
24 “No one can serve two masters. For you will hate one and love the other; you will be devoted to one and despise the other. You cannot serve both God and money. 25 “That is why I tell you not to worry about everyday life—whether you have enough food and drink, or enough clothes to wear. Isn’t life more than food, and your body more than clothing? 26 Look at the birds. They don’t plant or harvest or store food in barns, for your heavenly Father feeds them. And aren’t you far more valuable to him than they are? 27 Can all your worries add a single moment to your life? 28 “And why worry about your clothing? Look at the lilies of the field and how they grow. They don’t work or make their clothing, 29 yet Solomon in all his glory was not dressed as beautifully as they are. 30 And if God cares so wonderfully for wildflowers that are here today and thrown into the fire tomorrow, he will certainly care for you. Why do you have so little faith? 31 “So don’t worry about these things, saying, ‘What will we eat? What will we drink? What will we wear?’ 32 These things dominate the thoughts of unbelievers, but your heavenly Father already knows all your needs. 33 Seek the Kingdom of God[a] above all else, and live righteously, and he will give you everything you need. 34 “So don’t worry about tomorrow, for tomorrow will bring its own worries. Today’s trouble is enough for today.