Malachi 3:8-9 - Robbing (Hebrew-Qaba) God

Mal 3:8 - Will a man rob God? yet ye rob me. But ye say, Wherein have we robbed thee? In tithes and offerings.  

Mal 3:9 - Ye are cursed with the curse; for ye rob me, even this whole nation. (ASV) 

Robbery - Original Hebrew Word -, transliterated word - qâba‛, Phonetic spelling -kaw-bah', Meaning “to cover”, that is, (figuratively) defraud: - rob, spoil.

The people of Israel had robbed their Master, and misused his goods. They had asked, “In which shall we return? What have we done wrong?” And he soon gives them the answer.

There are few things to observe, 
The prophet's high charge exhibited, in God's name, against the people. They stand accused for robbery, for sacrilege, the worst of robberies: You have robbed me. He protests with them upon it: Will a man be so daringly rude as to rob God? Man, who is a weak creature, and cannot contend with God's power, will he think to rob him forcibly? Man, who lies open to God's knowledge, and cannot cover up himself from that, will he think to rob him? Man, who depends upon God, and derives his all from him, will he rob him that is his benefactor? This is ungrateful, unjust, and unkind, indeed; and it is very unwise thus to provoke him from whom our judgment proceeds. Robbing God is a dreadful crime. 
The people's high challenge in answer to that charge: But you say, in which have we robbed thee? They plead Not guilty, and put God upon the proof of it. Note, Robbing God is such a terrible crime that those who are guilty of it are not willing to own themselves guilty. They rob God, and know not what they do. They rob him of his honour, rob him of that which is devoted to him, to be employed in his service, rob him of themselves, rob him of sabbath-time, rob him of that which is given for the support of religion, and give him not his dues out of their estates; and yet they ask, in which have we robbed thee?

The plain proof of the charge, in answer to this challenge; it is in tithes and offerings. Out of these the priests and Levites had maintenance for themselves and their families; but they detained them, defrauded the priests of them, would not pay their tithes, or not in full, or not of the best; may be they brought not the offerings which God required, or brought the torn, and lame, and sick, which were not fit for use. They were all guilty of this sin, even the whole nation, as if they were in confederacy against God, and all combined to rob him of his dues and to stand by one another in it when they had done. The people kept back from the priests and Levites, his ministers, what was due to them; so that the Divine worship is neglected and which, being no other than a spoiling or robbing of them, might be interpreted a robbing of God.

The offerings included several classes of dues to God: 

=> the first fruits ; 

=> the annual half-shekel (Ex 30:13-15); 

=> the offerings made for the tabernacle (Ex 25:2-3; Ex 35:5, Ex 35:21, Ex 35:24; Ex 36:3, Ex 36:6) and the second temple (Ezra 8:25) at its first erection; it is used of ordinary offerings; 

=> of the tithes of their own tithes, which the Levites paid to the priests (Num 18:26, Num 18:28-29); 

=> of the portions of the sacrifice which accrued to the priests (Lev 7:14).

We are exhorted to pay the tithes and offerings to the Lord, else being guilty of robbing God. One of the best ways of receiving God’s blessings is through giving to the Lord, first that which belongs to Him and then as we wish, to show our love for Him. God loves a cheerful giver.