No two Muslims meet and shake hands except that their sins are forgiven before they part (from each other).[Ahmad]
"مَا مِنْ مُسْلِمَينِ يَلْتَقِيَانِ فَيَتَصَافَحَانِ إِلاَّ غُفِرَ لَهُمَا قَبْلَ أنْ يَفْتَرِقَا". (رواه أحمد)