This verse (chaupai) is from the Balakanda chapter of Shri Ramcharitmanas.
लखि सुबेष जग बंचक जेऊ। बेष प्रताप पूजिअहिं तेऊ॥ उघरहिं अंत न होइ निबाहू। कालनेमि जिमि रावन राहू॥
This verse (chaupai) is found at the beginning of Balakanda, discussing the significance of satsang (association with the righteous).
Meaning : Even those who are deceivers, when they appear in good (saintly) attire, are honored by the world due to the power of their appearance. However, one day, they are inevitably exposed. Their deception cannot last forever, just as it happened with Kalanemi, Ravana, and Rahu.