A person should begin Salah with the invocation of the beginning.
• It is desirable for the Imam (who leads people in Salah) to pause for a short time after Takbirat-ul-Ihram (saying: “Allahu Akbar [Allah is the Greatest]” upon starting Salah) for reciting Du`a’-ul-Istiftah.
The proof to that is the Hadith of Abu Hurayrah who said: “When the Prophet (peace be upon him) said Takbir (for the starting Salah), he would pause for a short time before reciting (Al Fatihah). Ao, I said: O Messenger of Allah, I have seen that you keep silent between the Takbir and recitation. What do you say? He said: O Allah, distance between me and my sins as wide apart between the east and the west.” [Reported by Al Bukhari and Muslim].
This Hadith contains two benefits:
1- Du`a’-ul-Istiftah is recited after Takbir.
2- Du`a’-ul-Istiftah is recited secretly because of his saying in the Hadith (pause for a short time).
• Du`a’-ul-Istiftah is a Sunnah.
• Ibn Hubayrah said in his book Al Ifsah 1/124: “Scholars have agreed that Du`a’-ul-Istiftah (opening supplication when starting Salah) in Salah is a Sunnah except the view of Imam Malik who said: it is not a Sunnah. Its description according to Abu Hanifah and Ahmad is to say: Subhanakal-lahumma wabihamdika.. (Glory be to You and Praise be to You). Its description according to Al Shafi`y is: Wajjahtu Wajhi Liladhy Fatara As-Samawat… (I have turned my face sincerely to the One who created heavens). Abu Yusuf said: It is desirable to combine both forms, and this is my choice.
Excerpted from: Al Fiqh Al Wadih on the school of fiqh and the preponderant view in Zad Al Mustaqna` (the book of Salah).