Sayyiduna Ibn Abbas (may Allah be pleased with them both) and Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) used to teach us the istikharah just as he would teach us a surah of the Qur'an: "O Allah, I seek good from You through Your knowledge, and I ask You for power through Your power, for You have power and I have none, You know and I do not know, and You are the Knower of the unseen. O Allah, whatever decree You have made concerning me, make its outcome good."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11429