Luke 16:10-13
He that is faithful in that which is least is faithful also in much: and He that is unjust in the least is unjust also in much.
If therefore ye have not been faithful in the unrighteous mammon, who will commit to your trust the true riches?
And if ye have not been faithful in that which is another man's, who shall give you that which is your own?
No servant 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.
Faithfulness refers to loyalty. When you are not faithful you are disloyal.When an assignment is committed to you, your faithfulness proves how loyal you are. Faithfulness brings promotion. When you are faithful at the level where you are, you can be trusted with a higher level.