What is the reward for patience in the face of a brother's death, and is death in a traffic accident considered martyrdom?

When a Muslim is afflicted by a calamity, such as the loss of a loved one, he should say: "Indeed, we belong to Allah, and indeed to Him we will return." Then he should be patient and seek his reward from Allah, for the Messenger of Allah, may Allah bless him and grant him peace, said: "There is no servant afflicted by a calamity who says: 'Indeed, we belong to Allah, and indeed to Him we will return. O Allah, reward me in my calamity and replace it with something better,' except that Allah will reward him in his calamity and replace it with something better." And the patient will be given their reward without reckoning.