Valmiki Ramayana Yuddha Kanda Sarga 87 Shloka 16

यः he who, स्वपक्षम् own side, परित्यज्य renouncing, परपक्षम् others side, निषेवते seeks refuge, सःhe, स्वपक्षे own side, क्ष्यम् destruction, प्राप्ते happens, पश्चात् whose refuge was sought, तैरेव by them only, हन्यते destroyed

"He who renounces his own kind and seeks refuge from others, will be destroyed by others whose refuge he sought when his own people are destroyed."