This hadith is a parable and shows a lot of meanings, however they are concentrated about the virtue of the Muslim ummah.
As to how this work time/wages can be interpreted, some scholars among them imam ibn Hajar in his literal interpretation stated that the comparison is rather to be taken from the point of view that Muslims are the last of these ummahs (the last to get revelation and follow their prophet()). For instance Christians would always have 600+ years more than Muslims of time.
There's a similar narration on the authority of abu Musa:
The Prophet (ﷺ) said, "The example of Muslims, Jews and Christians is like the example of a man who employed laborers to work for him from morning till night. They worked till midday and they said, 'We are not in need of your reward.' So the man employed another batch and said to them, 'Complete the rest of the day and yours will be the wages I had fixed (for the first batch). They worked until the time of the `Asr prayer and said, 'Whatever we have done is for you.' He employed another batch. They worked for the rest of the day till sunset, and they received the wages of the two former batches."
The context of this narration
This hadith must also be understood in context of the verse:
You are the best nation produced [as an example] for mankind. You enjoin what is right and forbid what is wrong and believe in Allah . If only the People of the Scripture had believed, it would have been better for them. Among them are believers, but most of them are defiantly disobedient. (3:110)
and some other verses adding explanation to this verse like:
And whoever desires other than Islam as religion - never will it be accepted from him, and he, in the Hereafter, will be among the losers. (3:85)
... And whoever denies the faith - his work has become worthless, and he, in the Hereafter, will be among the losers. (5:5)
And it was already revealed to you and to those before you that if you should associate [anything] with Allah , your work would surely become worthless, and you would surely be among the losers." (39:65)
O you who have believed, fear Allah and believe in His Messenger; He will [then] give you a double portion of His mercy and make for you a light by which you will walk and forgive you; and Allah is Forgiving and Merciful. (57:28)
and many more.
And other hadith narrations such as:
We are the last and would be the first on the Day of Resurrection.
(See for example in Sahih Muslim and Sahih al-Bukhari)
I heard Allah's Messenger (ﷺ) (p.b.u.h) saying, "We (Muslims) are the last (to come) but (will be) the foremost on the Day of Resurrection though the former nations were given the Holy Scriptures before us. And this was their day (Friday) the celebration of which was made compulsory for them but they differed about it. So Allah gave us the guidance for it (Friday) and all the other people are behind us in this respect: the Jews' (holy day is) tomorrow (i.e. Saturday) and the Christians' (is) the day after tomorrow (i.e. Sunday)."
(See for example different versions in Sahih al-Bukhari and Sahih Muslim and elsewhere)
The Prophet (ﷺ) said, "Three persons will get their reward twice. (One is) a person who has a slave girl and he educates her properly and teaches her good manners properly (without violence) and then manumits and marries her. Such a person will get a double reward. (Another is) a believer from the people of the scriptures who has been a true believer and then he believes in the Prophet (ﷺ) (Muhammad). Such a person will get a double reward. (The third is) a slave who observes Allah's Rights and Obligations and is sincere to his master."
(See for example in Sahih al-Bukhari and Sahih Muslim)
Allah's Messenger (ﷺ), holding out his middle and index fingers, said, "My advent and the Hour's are like this (or like these)," namely, the period between his era and the Hour is like the distance between those two fingers, i.e., very short.
(See for example in Sahih al-Bukhari)
Some of the meanings of this hadith
here some examples or parables in this hadith:
- The example of the lifespan or time span of the Muslim ummah compared to earlier nations: Which was set equal to the time span between 'asr and maghrib (which is much shorter than the time span between dhohr and 'asr etc. as stated by scholars such ibn al-'Arabi) which is not even the quarter of the day time (daylight), this was referred to in the hadith as:
"Who will work for me from the Asr till sunset for two Qirats?"
- The example of the high wages for this nation compared to the other nations. Note that the wage for deeds and its amount is in the hand of Allah. See for example many verses in the qur'an like:
The example of those who spend their wealth in the way of Allah is like a seed [of grain] which grows seven spikes; in each spike is a hundred grains. And Allah multiplies [His reward] for whom He wills. And Allah is all-Encompassing and Knowing. (2:261)
Race toward forgiveness from your Lord and a Garden whose width is like the width of the heavens and earth, prepared for those who believed in Allah and His messengers. That is the bounty of Allah which He gives to whom He wills, and Allah is the possessor of great bounty. (57:21)
In the hadith the prophet () made the examples of an employer and three kinds of employees: The first employees worked a rather long time for a wage, the second worked a somewhat shorter time for the same wage while the third got the double of the others wage working even a bit less.
Furthermore be aware that all our deeds only count if we believe as the verses and narrations I quoted above show!
- The reward or wage for this nation which is fixed and won't be lost because they believe in Allah and his prophet () while Alah said about those who disbelieved:
And We will regard what they have done of deeds and make them as dust dispersed. (25:23)
Here the prophet () set the Jews and Christians similar to those who worked for a specific task or daytime (by believing only in their messengers and rejecting others), the hadith could be understood like this:
Some workers worked from the morning until noon and refused to go ahead (and the employer refused to "fully pay" them as the task was incomplete), others worked from noon till 'asr time and accepted to complete or go ahead with the work of the former workers. But at 'asr time -without completing the full task- they refused to go ahead working (and also didn't get their "full payment"). So the "employer" asked a third group to complete the work of the former groups and rewarded them the double.
But the task was to believe in Allah and his prophets and some stopped believing in the later at a certain stage while the last ones believed in all.