SHAFAQNA (Shia International News Association) – It is narrated from Imam Reza (AS) who said: Perform Night Prayers (Salatul Layl). If a servant of God wakes up at the end of the night and perform 8 rokats of Salatul Layl, 2 Rokats of Salatul Shaf’a, one Rokat of Salatul Watr and in Qonoot ask for forgiveness from the Almighty (Isteqfar) 70 times, will be saved from the torments of the grave and the hellfire as well as prolonging his/her life and increase of his/her sustenance .
In another narration, Ahmad ibn Ali Ansari said: I heard from Raja ibn Abizahhak who said: Imam Reza (AS) in Qonoot of Salatul Watr asked for forgiveness from God (Isteqfar) 70 times .
 Beharul Anwaar, Vol. 87, Page 161.
 As above, Vol. 49, page 93.
[Please refer to Mafatihul Janan or other authentic sources for how to perform Salatul Layl]