The Messenger is Muhammad (saws) and the speech is directed to the people of Scripture.

(… عَلَىٰ فَتْرَةٍ مِّنَ الرُّسُلِ …) (…after a period [of suspension] of messengers,…): The period of suspension is about 600 years.

(… مَا جَاءَنَا مِن بَشِيرٍ وَلَا نَذِيرٍ …) (…“There came not to us any bringer of good tidings or a warner.”…): The good tiding about the Paradise and the warning about the Hellfire.

(  وَاللَّهُ عَلَىٰ كُلِّ شَيْءٍ قَدِيرٌ … ) (And Allah is over all things competent): Everything is under Allah’s absolute ability since He (swt) is the Creator and the decreed matters by His word (Be):

 فَإِذَا قَضَىٰ أَمْرًا فَإِنَّمَا يَقُولُ لَهُ كُن فَيَكُونُ

(and when He decrees a matter, He but says to it, “Be,” and it is.) (Ghafer: 68)