Valmiki Ramayana Ayodhya Kanda Sarga 20 Shloka 43

यः whoever, कश्चित् any one, माम् me, सेवते serving, अथवा or, अनुवर्तते following me, सः जनः such person, कैकेय्याः Kaikeyi's, पुत्रम् son, अन्वीक्ष्य having seen, नाभिभाषते हि will not talk to me.

Any one who serves me or follows me will not talk to me after seeing Bharata (installed as heirapparent).