The Prophet (ﷺ) used to say during the slaughter-

بِسْمِ اللَّهِ وَاللَّهُ أَكْبَرُ هَذَا عَنِّي وَعَمَّنْ لَمْ يُضَحِّ مِنْ أُمَّتِي

Bismillah-hi wallahu akbaru haza 'anni wa amman lam udahh-hi min ummati

In the name of Allah, Allah is Most Great. This is from me and from those who did not sacrifice from my community.

Reference: Sahih. Abu Dawud: 2810