• رَّٰسِخُون

Appears 2 times in the Quran.

1. 3:7 هُوَ ٱلَّذِىٓ أَنزَلَ عَلَيْكَ ٱلْكِتَٰبَ مِنْهُ ءَايَٰتٌ مُّحْكَمَٰتٌ هُنَّ أُمُّ ٱلْكِتَٰبِ وَأُخَرُ مُتَشَٰبِهَٰتٌ فَأَمَّا ٱلَّذِينَ فِى قُلُوبِهِمْ زَيْغٌ فَيَتَّبِعُونَ مَا تَشَٰبَهَ مِنْهُ ٱبْتِغَآءَ ٱلْفِتْنَةِ وَٱبْتِغَآءَ تَأْوِيلِهِۦ وَمَا يَعْلَمُ تَأْوِيلَهُۥٓ إِلَّا ٱللَّهُ وَٱلرَّٰسِخُونَ فِى ٱلْعِلْمِ يَقُولُونَ ءَامَنَّا بِهِۦ كُلٌّ مِّنْ عِندِ رَبِّنَا وَمَا يَذَّكَّرُ إِلَّآ أُو۟لُوا۟ ٱلْأَلْبَٰبِ

   He it is Who has revealed the Book to you; some of its verses are decisive, they are the basis of the Book, and others are allegorical; then as for those in whose hearts there is perversity they follow the part of it which is allegorical, seeking to mislead and seeking to give it (their own) interpretation. but none knows its interpretation except Allah, and those who are firmly rooted in knowledge say: We believe in it, it is all from our Lord; and none do mind except those having understanding.
   

2. 4:162 لَّٰكِنِ ٱلرَّٰسِخُونَ فِى ٱلْعِلْمِ مِنْهُمْ وَٱلْمُؤْمِنُونَ يُؤْمِنُونَ بِمَآ أُنزِلَ إِلَيْكَ وَمَآ أُنزِلَ مِن قَبْلِكَ وَٱلْمُقِيمِينَ ٱلصَّلَوٰةَ وَٱلْمُؤْتُونَ ٱلزَّكَوٰةَ وَٱلْمُؤْمِنُونَ بِٱللَّهِ وَٱلْيَوْمِ ٱلْءَاخِرِ أُو۟لَٰٓئِكَ سَنُؤْتِيهِمْ أَجْرًا عَظِيمًا

   But the firm in knowledge among them and the believers believe in what has been revealed to. you and what was revealed before you, and those who keep up prayers and those who give the poor-rate and the believers in Allah and the last day, these it is whom We will give a mighty reward.