It is narrated from Sayyiduna al-Fadl bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Prayer is two by two (rak'ahs), with a tashahhud in every two rak'ahs; and (prayer) is adopting complete humility, lowliness, calm and dignity. Then you raise both your hands." He (peace and blessings be upon him) said (in explanation of this): "You raise both your hands towards your Lord in such a way that their palms face your face, and you say: 'Ya Rabbi, ya Rabbi' (O my Lord, O my Lord). Whoever does not do this, then it (his prayer) is deficient and incomplete."
Hadith Referenceمسند أبي يعلى الموصلي / مسند الفضل بن العباس رحمه الله / 6738
Hadith Takhrij«أخرجه سنن الترمذي برقم: 385، وأخرجه مسند أحمد برقم: 17071، وأخرجه مسند البزار برقم: 2169، وأخرجه المعجم الأوسط للطبراني برقم: 8627، وأخرجه شرح مشكل الآثار برقم: 1091، وأخرجه شرح السنة برقم: 740، مسند ابویعلیٰ ترقیم الاثری: 6706»