Alqamah bin Wa'il bin Hujr (may Allah have mercy on him) narrates from his father (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) bowed, he kept his fingers apart, and when he prostrated, he kept them together.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2695