Valmiki Ramayana Ayodhya Kanda Sarga 61 Shloka 16
Original Shlokaन परेणाऽहृतं भक्ष्यं व्याघ्रः खादितुमिच्छति। एवमेतन्नरव्याघ्रः परलीढं न मन्यते।।2.61.16।।
1 source checked for this shloka
व्याघ्रः tiger, परेण by some other animal, आहृतम् procured, भक्ष्यम् food, खादितुम् to eat, न इच्छति does not like, एवं in the same way, नरव्याघ्रः the (best) among men (Rama), एतत् परलीढम् enjoyed by others, न मन्यते will not accept.
Just as a tiger will not eat the food acquired by another beast, Rama, the tiger (best) among men will not accept the kingdom enjoyed by others.