One should learn how to associate with the devotees of the Lord by gathering with them to chant the glories of the Lord. This process is most purifying. As devotees thus develop their loving friendship, they feel mutual happiness and satisfaction and by thus encouraging one another they are able to give up material sense grantification, which is the cause of all suffering. — Srimad Bhagavatam, 11.03.30.
To chant God's holy name means to associate directly with Him.
In the sun there is great heat and light, and by reflecting the greatness of the sun's light, the moon in night also appears great. Actually the moon is by nature dark ans cold, but in association with sun it has become accepted as great. Hence by association of the Great, one appears great.
To associate with the holy name and chant the holy name is to associate with the Personality of Godhead directly.
Association is very important. It acts just like a crystal stone, which will reflect anything which is put before it.
Nectar of Devotion, Chapter 12,