"Abdullãh ibne-'Amr Radiyallãhu 'anhuma narrates that Rasúlullãh (saw) said: He who turns with repentance a year before his death, his taubah is accepted, or even if a month before, or a week before, or a day before, or a Sã'ãt (about twenty three minutes), or even to the extent of time between two milking of a she-camel.
(Mustadrak Hakim)