The Quran root م ر ض m-r-ḍ

فِي قُلُوبِهِم مَّرَضٌ فَزَادَهُمُ اللَّهُ مَرَضًا وَلَهُمْ عَذَابٌ أَلِيمٌ بِمَا كَانُوا يَكْذِبُونَ ١٠

مَّرَضٌ maraḍun · (is) a disease

In their hearts is disease, so Allāh has increased their disease; and for them is a painful punishment because they [habitually] used to lie. (Surah Al-Baqarah, 2:10)

فَتَرَى الَّذِينَ فِي قُلُوبِهِم مَّرَضٌ يُسَارِعُونَ فِيهِمْ يَقُولُونَ نَخْشَىٰ أَن تُصِيبَنَا دَائِرَةٌ فَعَسَى اللَّهُ أَن يَأْتِيَ بِالْفَتْحِ أَوْ أَمْرٍ مِّنْ عِندِهِ فَيُصْبِحُوا عَلَىٰ مَا أَسَرُّوا فِي أَنفُسِهِمْ نَادِمِينَ ٥٢

مَّرَضٌ maraḍun · (is) a disease

So you see those in whose hearts is disease [i.e., hypocrisy] hastening into [association with] them, saying, "We are afraid a misfortune may strike us." But perhaps Allāh will bring conquest or a decision from Him, and they will become, over what they have been concealing within themselves, regretful. (Surah Al-Ma'idah, 5:52)

أَيَّامًا مَّعْدُودَاتٍ فَمَن كَانَ مِنكُم مَّرِيضًا أَوْ عَلَىٰ سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ وَعَلَى الَّذِينَ يُطِيقُونَهُ فِدْيَةٌ طَعَامُ مِسْكِينٍ فَمَن تَطَوَّعَ خَيْرًا فَهُوَ خَيْرٌ لَّهُ وَأَن تَصُومُوا خَيْرٌ لَّكُمْ إِن كُنتُمْ تَعْلَمُونَ ١٨٤

مَّرِيضًا marīḍan · sick

[Fasting for] a limited number of days. So whoever among you is ill or on a journey [during them] - then an equal number of other days [are to be made up]. And upon those who are able [to fast, but with hardship] - a ransom [as substitute] of feeding a poor person [each day]. And whoever volunteers good [i.e., excess] - it is better for him. But to fast is best for you, if you only knew. (Surah Al-Baqarah, 2:184)

وَإِذَا مَرِضْتُ فَهُوَ يَشْفِينِ ٨٠

مَرِضْتُ mariḍ'tu · I am ill

And when I am ill, it is He who cures me (Surah Ash-Shu'ara, 26:80)