Ramana Maharshi - Upadesa Saram, #10:

"The practice of fixing the mind in its own
source in the Heart is, without doubt, true

bhakti yoga and understanding."

when Maharshi was asked "what is the Heart referred to....?"

he replied, "That which is the source of all, that in which

all live, and that into which all finally merge,

is the Heart referred to."

Bhagavan Ramana Jai!