The holy name

Chant with attention and faith

Chant with faith and hear the name as you say it. Inattention, or holding on to worldly attachments, takes away from the chanting.

The tenth of the offenses to avoid covers three things: lacking full faith in the chanting, staying attached to worldly things after you have heard its glories, and being inattentive while you chant. You will not give your whole mind every time, so when it wanders, bring it back to the sound, gently and without scolding yourself. A calm place and a fixed time help.

Whose teaching
Padma Purāṇa
Where it is taught
The ten offenses to the holy name
Source
ISKCON Bangalore