﴿ ۞ قَالَتِ ٱلْأَعْرَابُ ءَامَنَّا ۖ قُل لَّمْ تُؤْمِنُوا۟ وَلَٰكِن قُولُوٓا۟ أَسْلَمْنَا وَلَمَّا يَدْخُلِ ٱلْإِيمَٰنُ فِى قُلُوبِكُمْ ۖ وَإِن تُطِيعُوا۟ ٱللَّهَ وَرَسُولَهُۥ لَا يَلِتْكُم مِّنْ أَعْمَٰلِكُمْ شَيْـًٔا ۚ إِنَّ ٱللَّهَ غَفُورٌۭ رَّحِيمٌ ﴾

“THE BEDOUIN say, “We have attained to faith.” Say [unto them, O Muhammad]: “You have not [yet] attained to faith; you should [rather] say, ‘We have [outwardly] surrendered’ - for [true] faith has not yet entered your hearts. But if you [truly] pay heed unto God and His Apostle, He will not let the least of your deeds go to waste: for, behold, God is much-forgiving, a dispenser of grace.””

Please check ayah 49:18 for complete tafsir.