Does it say anywhere in the Bible that we should test God? Well Jesus specifically says not to tempt Him (Luke 4:12). But in one case He says we can:

Malachi 3:8-12
8 "Will a man rob God? Yet you are robbing Me! But you say, 'How have we robbed Thee?' In tithes and offerings. 9 "You are cursed with a curse, for you are robbing Me, the whole nation of you 10 "Bring the whole tithe into the storehouse, so that there may be food in My house, and test Me now in this," says the LORD of hosts, "if I will not open for you the windows of heaven, and pour out for you a blessing until it overflows. 11 "Then I will rebuke the devourer for you, so that it may not destroy the fruits of the ground; nor will your vine in the field cast its grapes " says the LORD of hosts. 12 "And all the nations will call you blessed, for you shall be a delightful land," says the LORD of hosts.

Abraham commenced it:

Genesis 14:18-20
18 And Melchizedek king of Salem brought out bread and wine; now he was a priest of God Most High. 19 He blessed him and said, "Blessed be Abram of God Most High, Possessor of heaven and earth; 20 And blessed be God Most High, Who has delivered your enemies into your hand." He gave him a tenth of all.

Jacob continued it:

Genesis 28:11-22
11 He came to a certain place and spent the night there, because the sun had set; and he took one of the stones of the place and put it under his head, and lay down in that place. 12 He had a dream, and behold, a ladder was set on the earth with its top reaching to heaven; and behold, the angels of God were ascending and descending on it. 13 And behold, the LORD stood above it and said, "I am the LORD, the God of your father Abraham and the God of Isaac; the land on which you lie, I will give it to you and to your descendants. 14 "Your descendants will also be like the dust of the earth, and you will spread out to the west and to the east and to the north and to the south; and in you and in your descendants shall all the families of the earth be blessed. 15 "Behold, I am with you and will keep you wherever you go, and will bring you back to this land; for I will not leave you until I have done what I have promised you." 16 Then Jacob awoke from his sleep and said, "Surely the LORD is in this place, and I did not know it." 17 He was afraid and said, "How awesome is this place! This is none other than the house of God, and this is the gate of heaven." 18 So Jacob rose early in the morning, and took the stone that he had put under his head and set it up as a pillar and poured oil on its top. 19 He called the name of that place Bethel; however, previously the name of the city had been Luz. 20 Then Jacob made a vow, saying, "If God will be with me and will keep me on this journey that I take, and will give me food to eat and garments to wear, 21 and I return to my father's house in safety, then the LORD will be my God. 22 "This stone, which I have set up as a pillar, will be God's house, and of all that You give me I will surely give a tenth to You."

Moses confirmed it:

Leviticus 27:30-32
30 "Thus all the tithe of the land, of the seed of the land or of the fruit of the tree, is the LORD'S; it is holy to the LORD. 31 "If, therefore, a man wishes to redeem part of his tithe, he shall add to it one-fifth of it. 32 "For every tenth part of herd or flock, whatever passes under the rod, the tenth one shall be holy to the LORD.

Galatians 3:16-17
16 Now the promises were spoken to Abraham and to his seed. He does not say, "And to seeds," as referring to many, but rather to one, "And to your seed," that is, Christ. 17 What I am saying is this: the Law, which came four hundred and thirty years later, does not invalidate a covenant previously ratified by God, so as to nullify the promise.

Proverbs 3:5-10
5 Trust in the LORD with all your heart And do not lean on your own understanding. 6 In all your ways acknowledge Him, And He will make your paths straight. 7 Do not be wise in your own eyes; Fear the LORD and turn away from evil. 8 It will be healing to your body And refreshment to your bones. 9 Honor the LORD from your wealth And from the first of all your produce; 10 So your barns will be filled with plenty And your vats will overflow with new wine.

Malachi Commanded it:

Malachi 3:8-12
8 "Will a man rob God? Yet you are robbing Me! But you say, "How have we robbed You?' In tithes and offerings. 9 "You are cursed with a curse, for you are robbing Me, the whole nation of you! 10 "Bring the whole tithe into the storehouse, so that there may be food in My house, and test Me now in this," says the LORD of hosts, "if I will not open for you the windows of heaven and pour out for you a blessing until it overflows. 11 "Then I will rebuke the devourer for you, so that it will not destroy the fruits of the ground; nor will your vine in the field cast its grapes," says the LORD of hosts. 12 "All the nations will call you blessed, for you shall be a delightful land," says the LORD of hosts.

Jesus Commended it:

Luke 11:42
But woe to you Pharisees! For you pay tithe of mint and rue and every kind of garden herb, and yet disregard justice and the love of God; but these are the things you should have done without neglecting the others.

Matthew 23:23
Woe to you, scribes and Pharisees, hypocrites! For you tithe mint and dill and cummin, and have neglected the weightier provisions of the law: justice and mercy and faithfulness; but these are the things you should have done without neglecting the others.

Acts 20:35
In everything I showed you that by working hard in this manner you must help the weak and remember the words of the Lord Jesus, that He Himself said, "It is more blessed to give than to receive.'

More Verses:

Malachi 1:8
But when you present the blind for sacrifice, is it not evil? And when you present the lame and sick, is it not evil? Why not offer it to your governor? Would he be pleased with you? Or would he receive you kindly?" says the LORD of hosts.

Matthew 10:7-8
7 "And as you go, preach, saying, 'The kingdom of heaven is at hand.' 8 "Heal the sick, raise the dead, cleanse the lepers, cast out demons. Freely you received, freely give.

Mark 12:41-45
41 And He sat down opposite the treasury, and began observing how the people were putting money into the treasury; and many rich people were putting in large sums. 42 A poor widow came and put in two small copper coins, which amount to a cent. 43 Calling His disciples to Him, He said to them, "Truly I say to you, this poor widow put in more than all the contributors to the treasury; 44 for they all put in out of their surplus, but she, out of her poverty, put in all she owned, all she had to live on."

II Corinthians 9:6-10
6 Now this I say, he who sows sparingly will also reap sparingly, and he who sows bountifully will also reap bountifully. 7 Each one must do just as he has purposed in his heart, not grudgingly or under compulsion, for God loves a cheerful giver. 8 And God is able to make all grace abound to you, so that always having all sufficiency in everything, you may have an abundance for every good deed; 9 as it is written, "HE SCATTERED ABROAD, HE GAVE TO THE POOR, HIS RIGHTEOUSNESS ENDURE FOREVER." 10 Now He who supplies seed to the sower and bread for food will supply and multiply your seed for sowing and increase the harvest of your righteousness;