Abu Hurairh narrated that :
Allah's Messenger said: "Whoever performs Wudu, performing his Wudu well, then he comes to the Friday (prayer), and he gets close, listens and is silent, then whatever (sin) was between that and (the last) Friday are forgiven for him, in addition to three days. And whoever touches the pebbles, he has committed Lagha (useless activity)."