This chaupai appears in the Sundarkanda section of Shri Ramcharitmanas.

प्रबिसि नगर कीजे सब काजा। हृदयँ राखि कोसलपुर राजा॥ गरल सुधा रिपु करहिं मिताई। गोपद सिंधु अनल सितलाई॥
Context: where this chaupai appears in Shri Ramcharitmanas
This is the second half of the same Sundarkanda episode, when Hanuman ji is about to enter Lanka and Lankini blesses him. Its meaning: for one who keeps Shri Ram, the King of Kosalpur, in the heart, poison becomes nectar, enemies turn into friends, the ocean shrinks to a cow's hoofprint, and fire turns cool.
Read the complete episode containing this chaupai in Shri Ramcharitmanas, also known as the Tulsi Ramayana.
Read the full episode in Shri RamcharitmanasTransliteration
Prabisi Nagar Kije Sab Kaja. Hridayan Rakhi Kosalpur Raja.. Garal Sudha Ripu Karahin Mitai. Gopad Sindhu Anal Sitalai..
In Latin script this chaupai is also written as “Garal Sudha Ripu Karahin Mitai” or “Garal Sudha Ripu Kare Mitai”. The spelling varies; the verse is the same.
Word meanings
- Garal = poison
- Sudha = nectar
- Ripu = enemy
- Mitai = friendship
- Gopad = a cow's hoofprint
- Sindhu = ocean
- Anal = fire
- Sitalai = coolness
As a Shalaka answer
This is a most excellent answer. With remembrance of Shri Ram, even adverse circumstances turn favourable; there is no doubt about success; proceed with the Lord's name in your heart.