It depends on the circumstances under which you are talking to him.

If you want to win his favor, praise him wherever he is humble. Usually after getting your repeated affirmation, he will happily stop being modest.

If you have something serious to say to him, don’t praise him. The more you praise him, the more humble he will be, and he will end up talking nonsense! Say things with a normal heart, and say goodbye with a smile. Don't be condescending to him because he is humble, and don't compete with him to see who is more humble. Treat him as an equal. This will at least not offend him.