إِلَى رَبِّكِ

 إِلَى رَبِّكِ is a phrase (شِبْهُ الجُمْلَةِ) consisting of a genitive particle and a possessive nominal compound

PhraseParticle / Noun / NounNounNoun Particle
شِبْهُ الجُمْلَةِجَارٌ وَمَجْرُوْرٌ وَهُوَ مُضَافٌ وَ مُضَافٌ إِلَيْهِمُضَافٌ إِلَيْهِاسْمٌ مَجْرُوْرٌ وَهُوَ مَضَافٌحَرْفُ جَرٍّ
PhraseCompoundPossessive NounGenitive noun + Noun possessedParticle of pulling down
  
to your Lordإِلَى رَبِّكِ=كِ+رَبِّ+إِلَى
to your Lordyourslord ofto
Surah/Below is the only verse in the holy Quran containing the compound إِلَى رَبِّكِ
Verse
89-28Return to your Lord well pleased and well pleasingارْجِعِى إِلَى رَبِّكِ رَاضِيَةً مَّرْضِيَّةً