'This' is the Prophet ﷺ. 'A warner' means one who warns with great warning. When the previous messengers, blessings and peace be upon them, had their message established in the souls and settled in the hearts, such that it is not permissible to deny it, he had informed about the denial of those who rejected them due to their denial, and their salvation and the salvation of those who believed in them due to their support. There was no difference between him ﷺ and them in that except that the mercy towards him is more profound and predominant, encouraging following him and warning against opposing him. He said: 'From the early warners.' What is obligatory for him is what was obligatory for them, and you are like the early warners. So beware of what befell the deniers among them and hope for what was for the believers.