What is the ruling on fasting for a kidney transplant patient who drinks a lot of fluids and takes medication regularly, knowing that the transplanted kidney is functioning at 65 or 70 percent?

If a trustworthy Muslim doctor informs you that fasting will negatively affect your kidneys, then you are not permitted to fast, based on the Almighty's saying: "And do not kill yourselves. Indeed, Allah is to you ever Merciful." If the illness is one from which recovery is hoped, then you must make up the days you missed after recovery, based on the Almighty's saying: "So whoever among you is ill or on a journey [during them] - then [he is to fast] an equal number of other days." If the illness is one from which recovery is not hoped, then you must feed a poor person for each day you missed, based on the Almighty's saying: "And upon those who are able [to fast, but with hardship] - a ransom [as substitute] of feeding a poor person." Al-Daraqutni narrated from Ibn Abbas that this concession is for the elderly who cannot fast or for the sick person who will not recover.