Every pious believer including the martyr will be dying with peace and will see Ahlul Bayt (AS) on his death, who will give him glad tidings about the Mecry of Allah for pious believers. Angles of mercy will also give the pious believer glad tidings and look after him. Martyrs never die, but remain alive in a type of life which we can not feel as Allah says in Quran (And say not of those who were killed in the Way of Allah as dead. Nay, they are living but you perceive not. (Sura 2, verse 154).
Every believer who dies on the love of Ahlul Bayt will die as a Shaheed. This is according to Hadeeth narrated from the Prophet Muhammad (SAWA) in Shia and Sunni books like
1- Tafseer Al-Zamakhshari V. 4,
2- Tafseer Al-Fakhr al-Raazi, V.27. P. 165.
3- Tafseer Al-Qurtubim V.16, P.22 and 23.
4- Tafseer Ibn Arabi, V. 2, P. 219.
5- 'Tafseer Al-Tha'aalibi, الثعالبي V. 5, P. 157.
6- Yanabee' Al-Mawaddah by Al-Qondoozi Al-Hanafi, V. 2, P.332.
Wassalam.