Valmiki Ramayana Ayodhya Kanda Sarga 24 Shloka 9
Original Shlokaकथं हि धेनु स्स्वं वत्सं गच्छन्तं नानुगच्छति। अहं त्वाऽनुगमिष्यामि यत्र पुत्र गमिष्यसि।।2.24.9.।।
1 source checked for this shloka
धेनुः cow, गच्छन्तम् wandering, स्वं वत्सम् its calf, कथं हि how, नानुगच्छति will not follow, पुत्र son, यत्र whereever, गमिष्यसि you will go, अहम् I, त्वा you, अनुगमिष्यामि will follow.
I shall follow you wherever you go, my son, like a cow following its calf. How is it possible for a cow not to follow its wandering calf?