Sheikh `Abd al-Wahhâb al-Turayrî, former professor at al-Imâm University in Riyadh
Voicing one’s intentions before prayer is an innovation, because prayer is an act of worship and the Prophet (peace be upon him) neither voiced his intentions out loud nor commanded us to do so.
When a Muslim intends to perform prayer, he is not requested to utter anything. He is worshipping Allah Who knows everything and knows the innermost secrets of each person and He knows that this person has made ablutions and went to mosque for this purpose. Therefore, your intention is, in fact, in your heart. Just start prayer without uttering any formula of intention.
Source: Islam Today