He thinks that you should pay it in full every month to build credit.
For example, let's say you have $800 in cash to buy an iPhone but you put it on your credit. He thinks that you should pay it all back As soon as possible, like the same day.
What I told him is that the banks like it when you pay it not in full ($800) but rather monthly with some interest in it. So that it increases your CC score. If it's two months or three months, etc.
Obviously if you miss payments that's a no no.
Added (1). So if I put $50 of gas on my card, I should run to the bank before it closes and pay for it? How will I build credit if I can't show the bank that I can pay for monthly payments on time. So what you're saying is that I should have 1 dollar of debt and pay for it every month? How would they trust me I play with the "low" numbers. What is a low balance?
Added (2). @StephenWeinstein Also btw my friend never said anything about a LOW BALANCE, he says pay it in full meaning no balance at all.
Read more: Is my friend idea on building credit wrong?