Abu Ubaydah bin Abdullah narrates from his father, Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), that he said: "Beware of these testimonies (claims), that you say: 'So-and-so was killed a martyr,' for one man fights out of (tribal) zeal, another fights in pursuit of worldly gain, and another fights merely to show off his bravery. But I will tell you what you can bear witness to: the Messenger of Allah (peace and blessings be upon him) dispatched a military detachment one day. Only a little time had passed when he (peace and blessings be upon him) stood up, praised and glorified Allah, and said: 'Your brothers have met the polytheists; they (the polytheists) martyred them and not one of them remained. (After their martyrdom) they said: "Our Lord, convey to our people that we are pleased (with our end) and our Lord is pleased with us." So I have come to you as their messenger: they are pleased, and (Allah) has been pleased with them.'" This hadith has a sahih (authentic) chain of narration if it is free from irsal (a break in the chain), for our Shaykhs differ over whether Abu Ubaydah heard from his father or not.