A martyr (shahid), in the eyes of Allah, is one who gives testimony to the truth of Islam even at the cost of his life. It means that man gives an unshakable proof of his fidelity to Islam and, by sacrificing his life, proves that there is nothing more precious and dear to him than the faith of Allah.
Martyrdom is closely connected with sincere devotion to Islam and it is achieved when the intention is purely the love of Allah. Sincerity of purpose is something which is hidden from the view of men. For, God alone knows the true motive of a man. It is, therefore, forbidden to say with a tone of certainty that so and so is a martyr and is surely entitled to Paradise.
As for sincerity of purpose, it is required not only in case of martyrdom. It is the very soul of integrity and uprightness.
The Muslims should refrain from saying anything with perfect certainty. The Muslims were calling that man a martyr but it was revealed to the Apostle of Allah that he was not so because he had not fought the battle for the Glory of Allah, but for the spoils of war and, therefore, he acted treacherously in regard to them. That only the believers would enter Paradise implies that only those persons would be admitted to Paradise who sincerely and faithfully, without having any worldly end before them believe in Allah and stand for Islam and then struggle for its cause. ¨