The Ruling on the Invocation at the Beginning of Ablution

Question:
The Shaykh: The questioner from Riyadh asks: Does omitting the invocation when performing ablution invalidate the ablution?

Answer:
A group of scholars consider the invocation obligatory along with the remembrance of Allah, except if one omits it out of forgetfulness or ignorance, in which case it does not harm. As for intentionally omitting it, one should not intentionally leave it out, but if one omits the invocation out of forgetfulness or ignorance, there is no blame on him.