Malachi 3:10 clearly states, "Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the LORD of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it."
So this means you will be blessed right? Let's take another look at the phrase "open up the windows of heaven". Look at Genesis Gen. 7:11-12 & Gen. 8:2. Also, look at I Kings 8:35. You see, God wasn't promising blessings. He was promising RAIN! This is why God continued in Malachi 3:11 by saying, "And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the LORD of hosts". You see, the Israelites inheritance was conditional also. If they obeyed God's commandments, He would continue to pour rain from the windows of heaven and their seeds would be blessed. If they disobeyed God's commandments, he would shut up the windows of heaven and stop the rain, causing a drought.