This phrase translates to the owner(Maalik) of judgement day(yawmid-deen).
A warning for self-reflection:
The first two verses were about how extremely loving and caring Allah (subhanahu wa ta’ala) is. In order for us to not take advantage of his Rahmah, Allah (subhanahu wa ta’ala) is reminding us that he is the owner of judgement day.
Allah (subhanahu wa ta’ala) didn’t use the word Rabb even though it includes Maalik because the meaning of Rabb also includes the one who takes care of, the giver of gifts. On judgement day Allah (subhanahu wa ta’ala) will not give any gifts. He will only be Maalik. This is scary and a warning for us to fix ourselves.
Word-by-word explanation
Maalik or Malik?
Some people recite the phrase as Maliki yawmid-deen which translates to King of judgement day. Both the recitations go back to Prophet Muhammad (sallallahu alaihi wasallam).
So Allah (subhanahu wa ta’ala) is both owner and king of judgement day. By Maalik, Allah (subhanahu wa ta’ala) is indicating that judgement day is his ownership and that no one has the right to question him on that day. By Malik, Allah (subhanahu wa ta’ala) is indicating that he is the judge on the judgement day as well i.e. whatever Allah (subhanahu wa ta’ala) says will be executed and he is the final authority and his verdict will be final.
Another interpretation is that, an owner usually controls smaller decisions whereas a king controls the major decisions. With Allah (subhanahu wa ta’ala) being both the owner and the king he will be controlling every single thing from the smallest deed of an individual to the bigger things like resurrecting all of mankind etc.
Yawm:
“Yawm” roughly means day. But the judgement day isn’t going to be a day of 24 hours. Its length would vary based on our imaan. If the imaan is stronger, the judgement day will be quicker and if the imaan is weak then the day gets longer and longer. According to Prophet Muhammad (sallallahu alaihi wasallam) for the perfect believer, a true momin, the time of judgement day would be like the time between Asr and Maghrib. And for the one with no imaan, a kaafir/faasiq/mushrik, it would be as long as 50,000 years. It would become so problematic/terrible that the kaafir would beg Allah (subhanahu wa ta’ala) for hell so that the day ends. Hence yawm doesn’t actually mean a day but the length of time.
But how can a day be that short or that long?
The first word that follows Maalik (owner) is Yawm (day). Allah (subhanahu wa ta’ala) is talking about the ownership of “day” which is something unique. It is unique because human beings can own a lot of things but they cannot own time. If Allah (subhanahu wa ta’ala) owns the day then he can stretch it to however long he wants and contract it however short he wants. Therefore yawmid-deen will actually depend on how good our imaan is.
Deen:
The word “deen” can be translated to the religious style of living. But another meaning of “deen” is judgement; the final retribution. Hence yawmid-deen is usually translated as day of judgement.
A better meaning for “yawmid-deen” is the day where everything is dealt with. This world by definition is unfair. There is no justice. On that day, Allah (subhanahu wa ta’ala) will reckon the creation for their deeds, evil for evil, good for good, except for those whom He pardons.
Hadith from Jami’ at-Tirmidhi
Shaddad bin Aws (radi allahu anhu) narrated that the Prophet (sallallahu alaihi wasallam) said: “The clever person is the one who subjugates his soul, and works for what is after death. And the incapable is the one who follows his desires and merely hopes in Allah (subhanahu wa ta’ala).”
[He said:] The meaning of his saying: “Who subjugates his soul”, is to say the one who reckons with his soul in the world, before he is reckoned with, on the Day of Judgement. It has been related that ‘Umar bin Al-Khattäb (radi allahu anhu) said: “Reckon with yourselves before you are reckoned with, and prepare for the Greatest Inquisition. The reckoning of the Day of Judgement is only light for the one who reckoned with himself in the world.” And, it has been related that Maimun bin Mihran said: “The slave (of Allah (subhanahu wa ta’ala)) will not be a Taqi until he has reckoned himself, just as he would account for where his business partner got his food and clothing.”
Some of the statements from Allah (subhanahu wa ta’ala) regarding judgement day in the Quran:
The Day that Ar-Ruh (Jibril (Gabriel) or another angel) and the angels will stand forth in rows, they will not speak except him whom the Most Gracious (Allah (subhanahu wa ta’ala)) allows, and he will speak what is right. (78:38)
And all voices will be humbled for the Most Gracious (Allah (subhanahu wa ta’ala)), and nothing shall you hear but the low voice of their footsteps. (20:108)
On the Day when it comes, no person shall speak except by His (Allah’s (subhanahu wa ta’ala)) leave. Some among them will be wretched and (others) blessed. (11:105)
Ad-Dahhak said that Ibn Abbas (radi allahu anhu) commented, “Allah (subhanahu wa ta’ala) says, ‘On that Day, no one owns anything that they used to own in the world.”’