Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto,Ontario, Canada, states that: “According to majority of scholars of Hadith and Fiqh, Duha Prayer, Al-Ishraq Prayer, and Al-Awwabin Prayer are all names of the same salah (ritual Prayer). It is a recommended Prayer without any fixed number of rak`ahs; its time proper starts a little after sun rise (approximately twenty minutes after sunrise) and extends up to the time of the declining of the sun from the meridian. The above view of the majority of scholars and jurists is based on the fact that there is no reason to make a distinction in the sources.
A minority of scholars, however, have made a distinction between Al-Ishraq Prayer and Duha Prayer. According to them, Al-Ishraq Prayer is done after sun rise (around twenty or so minutes after) while Duha Prayer is done much later.
There is no doubt that the first view is more authentic and more in conformity with the close study of the hadiths in this respect. Anyway, one must never make an issue out of this controversy, for, after all, it is an optional Prayer. Imam Ibn Al-Qayyim has cited the various views about the importance of this Prayer: Some say that one should not exaggerate its importance, and therefore do it only sparingly and not consistently, while others insist that it should be performed consistently. In other words, there is nothing in the sources to make it obligatory or even comparable to Witr Prayer in importance.
Even if someone, however, were to look at it favourably, it can never be taken literally, for it contradicts both sound hadiths and sound reason.
As for the precise intention to be formulated while praying Duha Prayer or Al-Ishraq Prayer, or others, there is no hard and fast rule to follow. Since it is an optional Prayer, it is enough to say in one’s mind that one is praying nafl or sunnah of Duha or Ishraq. One may perform any number of rak`ahs from a minimum of two rak`ahs up to preferably eight rak`ahs.”