Mohammad ibn Moslem narrated: I heard that Imam Baqir (AS) (the fifth Shia Imam) and Imam Ja’afar Sadeq (AS) (the sixth Shia Imam) said: Truly, Allah (SWT) rewarded Imam Hussain (AS) for his martyrdom by designating Imamate in his progenies, and cure in the soil of his grave, and accepting Dua near his grave, as well as the time spent by anyone visiting his grave not calculated as the age of that person. Mohammad ibn Moslem added: Then I asked Imam Sadeq (AS): for all this greatness and respect for his sacrifices, what will be given to Imam Hussain (AS)? Imam Sadeq (AS) replied: Indeed, he will join the Prophet (PBUH) and will be his companion at the same level and position. Then, Imam Sadeq (AS) recited Ayah 21 of Surah At-Tur: “And those who believe and whose children follow them in faith; to them shall God will join their children, nor shall God deprive them of the fruit of aught of their works; yet is each individual in pledge for his deeds.” .
 Amaali, Sheikh Toosi, Majlis Yaazdahum, Page 317.
Source: Shafaqna English