Shaykh Ibn ‘Uthaymeen advised:
I say that celebrating the birthday of the Prophet was not [something] known [to have been practiced] by the righteous predecessors.
The rightly guided leaders did not do that, and nor did the [other] companions [of the Prophet ﷺ] do that, and nor did those who followed them in good, and nor did the imaams of the Muslims after them.
And here, we ask…do we have more reverence for the Messenger ﷺ than they did? Answer [my question] O gathering! No [we do not].
Do we have more love for the Messenger ﷺ than they did? No [we do not].
If the matter is as such, then we must follow suit, and not practise the birthday of the Prophet ﷺ; Because it is an innovation.