It has been narrated on the authority of Abu Ishaq, who heard Bars' b. Azib say: When the Messenger of Allah (ﷺ) made peace with the people of Hudaibiya, 'Ali drew up the agreement between them, and so he wrote: Muhammad, the Messenger of Allah. (This is followed by the same wording as we have in the previous tradition except the omission of the words: This is what he has settled.)
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، قَالَ سَمِعْتُ الْبَرَاءَ بْنَ عَازِبٍ، يَقُولُ لَمَّا صَالَحَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَهْلَ الْحُدَيْبِيَةِ كَتَبَ عَلِيٌّ كِتَابًا بَيْنَهُمْ قَالَ فَكَتَبَ " مُحَمَّدٌ رَسُولُ اللَّهِ " ثُمَّ ذَكَرَ بِنَحْوِ حَدِيثِ مُعَاذٍ غَيْرَ أَنَّهُ لَمْ يَذْكُرْ فِي الْحَدِيثِ " هَذَا مَا كَاتَبَ عَلَيْهِ " .
sunnah.com