It is proven in the saheeh Sunnah that there are various kinds of martyrs who will attain the status of martyrdom in the Hereafter; this is by the grace and mercy of Allah.
It was narrated from Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “The martyrs are five: the one who dies of the plague, the one who dies of a stomach disease, the one who drowns, the one who is crushed beneath a falling wall, and the martyr who is killed for the sake of Allaah.”
Al-Haafiz Ibn Hajar (may Allah have mercy on him) said:
Ibn al-Teen said: All of these are deaths which involve hardship. Allah has bestowed His grace upon the ummah of Muhammad (blessings and peace of Allah be upon him) by making them means of erasing their sins and increasing their rewards, and enabling them to attain the status of martyrdom.
Fath al-Baari, 6/44
If a person dies of cancer, some of the scholars are of the view that he is included among the types of martyr mentioned in the hadeeth, on the basis that the word mabtoon (the one who dies of a disease in the abdomen) is general and includes everyone who dies of a disease in his abdomen and that this does not apply to any one specific disease.
Al-Nawawi (may Allah have mercy on him) said:
The word mabtoon means the one with a disease in the abdomen, which is diarrhoea. Al-Qaadi said: And it was said that he is the one who suffers from dropsy or oedema and swelling of the abdomen. And it was said that it refers to the one who suffers some disease in his abdomen. And it was said that it refers to anyone who dies from a disease in the abdomen in general. End quote from Sharh Muslim by al-Nawawi.
But it should be noted that this suggestion is connected to two conditions:
(i) that the site of the cancer be in the abdomen so that he may truly be said to be mabtoon.
Shaykh ‘Abd al-Muhsin al-‘Abbaad (may Allah preserve him) was asked:
Does a person who dies of cancer come under the heading of mabtoon?
No, because cancer is not always in the stomach; it may be somewhere other than the stomach.
Sharh Sunan Abi Dawood (tape no. 230)
As the site of your friend’s cancer was in the throat, he is not included among any of the groups who are regarded as martyrs.
(ii) that the disease should not have been caused by smoking, taking drugs or drinking alcohol, or other haraam things, unless he has repented sincerely from that and has given up consuming those haraam things.
This condition is general and applies to all those mentioned in the hadeeth. If a woman is pregnant as the result of zina and dies in labour, she is not regarded as one of the martyrs. If a person who drowned had boarded the boat or ship in order to commit sin or some immoral activity, and dies as a result of drowning, he is not one of the martyrs. A person who is killed by a falling wall when he is committing zina or drinking alcohol is not one of the martyrs. In the answer to question no. 45669, we have quoted the Standing Committee as saying that a person who dies as the result of a car accident when he was inside the car comes under the same heading as one who was killed by a falling wall, so he is a martyr, by Allah’s leave. But this cannot be applied to those foolish young men to whom this happens when they are racing in their cars, or to those who compete in difficult circumstances in the mountains or in the snow (“extreme sports”).
In the answer to question no. 22140, we quoted Shaykh al-Islam Ibn Taymiyah as saying that if a person drowns after boarding a ship for sinful purposes, he is not a martyr.
And elsewhere he said:
Whoever wants to follow a path where the possibilities of being safe or being killed are equal has to refrain from following it; if he does not refrain, then he is aiding in his own destruction so he is not a martyr.
Al-Fataawa al-Kubra, 5/381
Al-Suyooti (may Allah have mercy on him) said:
Al-Qurtubi said: This and the previous one -- i.e., those who are killed by a falling wall or drowning -- if they did not take risks and did not fail to take precautions, (then they are martyrs). But if they did not take precautions and died as a result of that, then they are sinners.
Al-Deebaaj ‘ala Muslim (4/508)
In al-Mawsoo‘ah al-Fiqhiyyah (26/273, 274) it says:
An exception is made in the case of one who travels for the purpose of sin and dies away from home. Another exception is made in the case of one who drowns but was sinning by boarding the ship when he knew that it was most likely not to be safe for him to do so, or he boarded it for the purpose of committing sin. Another exception is made in the case of a woman who is pregnant as a result of zina and dies in childbirth. End quote.
If the person who is slain in battle was fighting for the sake of tribalism or to show off, he does not attain the virtue or status of martyrdom, and it is more likely that such people will not attain that great reward.
Cancer in and of itself does not mean that the person who dies of it is one of the types of martyrs, unless the disease was in his abdomen. That is not what is stated in the hadeeth; rather it is the ijtihaad (opinion) of some scholars with regard to the meaning of mabtoon. If a person’s disease was caused by smoking and the like, and he dies of it before repenting, then he is not a martyr, even if the disease was in his abdomen. But if the disease in his abdomen was not the result of a haraam action, we hope that he will attain the status of the martyrs in the Hereafter, in sha Allah.
And Allaah knows best.