It is narrated from Sa'id bin Sam'an (may Allah have mercy on him) that Sayyiduna Abu Hurayrah (may Allah be pleased with him) came to us in the mosque of Banu Zurayq and said: There are three practices which the Messenger of Allah (peace and blessings be upon him) used to do, but the people have abandoned them. When he (peace and blessings be upon him) stood for the prayer, he would do like this; the narrator gestured with his hand, and he neither pressed the fingers of his hand tightly together nor spread them far apart.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2317