What is a siddiq, how does one become a siddiq, and how does one reach this rank?

The answer is found in the authentic hadith narrated by Ibn Hibban from Ibn Mas'ud and 'Amr ibn Murrah Al-Juhani, that the Prophet, peace and blessings be upon him, said to one who testified that there is no god but Allah and that you are the Messenger of Allah, performed the five daily prayers, paid the zakat, and fasted and prayed during Ramadan: "He is among the truthful (siddiqin) and the martyrs (shuhada')." In Ibn Khuzaymah's narration: "Whoever dies upon this will be among the truthful (siddiqin) and the martyrs (shuhada')."