When one pours water on the root of a tree, the trunk and branches of the tree are automatically pleased. Similarly, when one becomes a devotee of Lord Viṣṇu, everyone is served, for the Lord is the Supersoul of everyone.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
यथा हि स्कन्धशाखानां तरोर्मूलावसेचनम् । एवमाराधनं विष्णोः सर्वेषामात्मनश्च हि
yathā hi skandhaśākhānāṃ tarormūlāvasecanam | evamārādhanaṃ viṣṇoḥ sarveṣāmātmanaśca hi
SB 8.5.49