Philippians 4:19 ASV

One of the most well-known of the passages addressing God's provision. Paul boldly states that God will meet all the needs of the people he was writing to. For sure that's Christ-followers in Philippi, but there's no reason to think He didn't mean this as universal to Christ-followers.

The context here is interesting. A few verses before Paul makes the point that he is not asking for financial support because he is needy and want the Philippians to take care of that. In fact, he says, he has learned through Christ to be content in any situation - both when he is in need, and when he has plenty. And that regardless of the circumstances, he can do whatever is necessary through the strength God provides.

So, clearly Paul is not promising that Christians will always have excess, or even that they won't face trials or difficulties. But even acknowledging that fact, it's a pretty clear promise of God's provision.