Bara' ibne-'Azib Radiyallãhu 'anhuma narrates that Rasúlullãh (saw) said: When two Muslims meet. Shake hands, praise Allãh and seek forgiveness, their sins are forgiven. (For example, by saying Alhãmdulillãh, Praise be to Allãh; Yagfirullãhu lanã wa lakum, May Allãh forgive you and me.)

(Abu Dãwúd)