lianbeng replies: erm...it is, actually! check out Malachi 3:10 for reference!
Malachi 3:10 is one of the most 'popular' verses (if not the most 'popular' verse) used by church leaders as a basis to teach about tithing. One has to read the whole book in totality. This book is written to rebuke priests who were greedy, collecting tithes but refusing to share with the poor. In this book you read at least two times God rebuked the priests by these words: Oh, you priests! And not even one such rebuke was addressed to the temple goers.
Furthermore, the book is written many hundred years before the birth of Christ when tithing then was an Old Testament practice. There is no a single verse in the New Testament that teaches the NT Christians to give tithes. None of the 12 apostles practised giving tithes and none ever did tell Christians to tithe. Yes....there are many verses in the NT to tell people to give and share with the poor e.g. those who have lost their husbands, children who have lost their fathers or mothers. But this is not tithing. Tithes is NOT a New Testament teaching.
If you are interested to know about this especially to further understand whether tithings is a biblical teaching in the NT, you can go to google for this book which can be loaded free of charge:
Should Church Teach Tithing by Dr. Kelly (which is a church pastor). His conclusion: NO - tithing should not be taught in churches! Interestingly, the book noted that God collected tithes only from the Jews and not even one pagan (i.e. not Jews) had given tithes which were in the form of food, livestock (and never money though money was used years before tithing was practiced). Another point noted in the book is that tithing of food and livestock were limited to only in those produce within the Holy Land and was given only once (and not every month when you have your salary as what pastors and church leaders telling you today).
God bless
Psalm23