Valmiki Ramayana Ayodhya Kanda Sarga 75 Shloka 58

आर्यः esteemed one, यस्य whose, अनुमते with sanction, गतः exiled, भक्त्या by loyalty (to two religious factions), विवदमानेषु while disputing, मार्गम् one line of argument, आश्रित्य taking shelter, पश्यतः seeing, तस्य to him, पापेन by such sin, युज्येत will apply.

May that one who counselled the exile of my esteemed brother acquire the sin in the same way a person acquires while giving onesided judgement between divided religious disputants