Asim bin Damrah said: We asked Sayyiduna Ali (may Allah be pleased with him) about the voluntary prayers of the Prophet (peace and blessings be upon him) during the day. He said to us: Who is able to do that? We said: Tell us, and we will do as much of it as we are able. He said: After praying Fajr, the Prophet (peace and blessings be upon him) would wait until the sun had risen, its measure being that of Asr; then he would stand and pray two rak'ahs, separating them with the salam, invoking peace upon the angels brought near, the prophets, and the Muslims and believers who follow them. Then he would wait until the time of Duha, its measure being that of Zuhr; then he would stand and offer four rak'ahs, separating them with the salam and invoking peace upon the angels brought near, the prophets, and the Muslims and believers who follow them. Then he would wait until the sun passed its zenith; then he would offer four rak'ahs, separating them with the salam, invoking peace upon the angels brought near, the prophets, and the Muslims and believers who follow them. Then he would pray two rak'ahs after Zuhr, doing the same in them; then he would pray four rak'ahs before Asr, doing the same in them.
(b) In the narration of Isra'il there is the addition: He did not persist in them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4914