Tafsir of Az-Zukhruf 43:61

{And indeed, he is a sign for the Hour...}

{And indeed, he}—meaning Jesus, peace be upon him—{is a sign for the Hour}, that is, a condition among its conditions by which it is known. The condition is named a "sign" (‘alam) because knowledge (‘ilm) of the Hour is obtained through it.

Ibn Abbas recited it as li-‘alam (a landmark/marker). It was also recited as lil-‘alam (for knowledge). Ubayy recited it as li-dhikr (a reminder), naming that by which something is remembered a "reminder," just as that by which something is known is named a "sign."

In the Hadith: Jesus, peace be upon him, will descend upon a mountain pass in the Holy Land called Afiq. He will be wearing two light yellow garments, his hair will appear as if it were oiled, and in his hand will be a spear with which he will kill the Dajjal. He will come to Jerusalem while the people are in the dawn prayer and the Imam is leading them. The Imam will step back, but Jesus will bring him forward and pray behind him according to the Law (Shari‘ah) of Muhammad, peace be upon him. Then he will kill the swine, break the cross, destroy the churches and synagogues, and kill the Christians except for those who believe in him.

According to Al-Hasan, the pronoun refers to the Quran, meaning that through the Quran the Hour is known, because it contains the announcement of it.

{So do not doubt it}—from miryah, which is doubt.

{And follow me}—follow my guidance and my law, or follow my Messenger. It is said: This is a command for the Messenger of Allah to say: {This is a straight path}—meaning this which I call you to, or this Quran, if the pronoun in {And indeed, he} is taken to refer to the Quran.

{And do not let Satan avert you. Indeed, he is to you a clear enemy.}