Sayyiduna Ibn Umar (may Allah be pleased with them both) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever fasts on Wednesday, Thursday and Friday, then on Friday gives in charity whatever little of his wealth he can, every sin he has committed will be forgiven, until he becomes free of sins as on the day his mother gave birth to him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13251