Al-Bayhaqee relates from Ibn ‘Umar radiallaahu ‘anhu that AlIaah’s Messenger sallallaahu ‘alayhi wa sallam said:
“For everything there is a polish, and the polish for the hearts is the dhikr (remembrance) of Allaah.
There is nothing more potent in saving a person from the punishment of Allaah than the dhikr of Allaah.” It was said: Not even Jihaad in the path of Allaah. So he replied: “Not even if you were to continue striking with your sword until it breaks.” 
 Saheeh: Related by Ahmad (4/352), from Mu’aadh ibn Jabal radiallaahu ‘anhu. It was authenticated by al-Albaanee in Saheehul-Jaami’ (no.5644)
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