Allah mentioned the final destination of those foremost in faith, the nearest to Him, He next mentioned the end of those on the right, the righteous believers. Maymun bin Mihran said that those on the right side are lesser in rank than the foremost in faith. Allah said,
وَأَصْحَـبُ الْيَمِينِ مَآ أَصْحَـبُ الْيَمِينِ
(And those on the right -- how (fortunate) will be those on the right) who are those on the right, what is their condition and what will their final destination be like Allah next answers this question by saying,
فِى سِدْرٍ مَّخْضُودٍ
((they will be) among Sidr Makhdud.) Ibn `Abbas, `Ikrimah, Mujahid, Ibn Al-Ahwas, Qasamah bin Zuhayr, As-Safr bin Nusayr, Al-Hasan, Qatadah, `Abdullah bin Kathir, As-Suddi, Abu Hazrah and several others said, "The kind without thorns." And from Ibn `Abbas: "It is the one that is laden with fruits." This is also reported from `Ikrimah and Mujahid. Similar was also said by Qatadah as we mentioned. So it is the one with a full load of fruits without thorns. So it appears that both meanings apply here. The lote tree, of this life is thorny and carries few fruits. In the Hereafter, it is the opposite; it does not have thorns and carries plenty of fruit, the weight of which strains its trunk. `Utbah bin `Abd As-Sulami said, "I was sitting with Allah's Messenger ﷺ, when a bedouin came and said, `O Messenger of Allah! Have you heard about the tree that has more thorns than any other being in Paradise' Meaning the Talh tree. So Allah's Messenger ﷺ said:
ثُلَّةٌ مِّنَ الْأَوَّلِينَ وَثُلَّةٌ مِّنَ الْآخِرِينَ (many from the earlier generations, and many from the later ones....56:39-40) In connection with sabiqun, (the Foremost) two views of the commentators were quoted earlier as to the identity of 'the earlier' and the 'later' generations. If 'the earlier' refers to the generations from 'Adam (علیہ السلام) to the period just prior to the advent of the Holy Prophet ﷺ and 'the later generations' refers to the 'Ummah of the Holy Prophet ﷺ till the Day of Judgment, as some of the commentators have opined, then the verses would mean: 'the People of the Right' will constitute a 'large party' of believers and the righteous from all the previous communities combined together, while there will be a 'large party' from the Ummah of the Holy Prophet ﷺ alone. In this case, it is a great honor for the Ummah of the Holy Prophet ﷺ that, despite the short period they lived in this world, they could be compared to all the previous communities who were headed by hundreds of thousands of Prophets (علیہم السلام) . Besides, the words 'many from the later generations' has the scope of being larger in number than the 'many from the earlier generations'.
If we go by the second view of the commentators, who say that both 'earlier' and 'later' generations are from the ummah of the Holy Prophet ﷺ ، then even the later generations of this ummah will not be totally deprived of 'the Foremost', though their number in later generations will be less. As for the People of the Right, their number will be large in both 'earlier' and 'later' generations. This fact is proved by a Hadith reported by Bukhari and Muslim from Sayyidna Mu` awiyah ؓ in which the Holy Prophet ﷺ has said, 'A group of my 'Ummah will always remain on the truth and dominant, unharmed by those who fail to support them and those who defy them, until the Last Hour begins.'.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 26–39
The group at the forefront (as-sabiqun) will comprise of those who, immediately accept the Truth when it appears before them, and surrender themselves to it without hesitation. According to the Prophet’s wife, ‘A’ishah, the Prophet said, ‘Do you know, on the Day of Judgement, who will be the first to find a place in the protective shade of God?’ People said that God and His Prophet knew best. Then he said, ‘It will be those to whom Truth was presented and they accepted it. When Truth was demanded of them, they gave it. They gave the same decision with regard to others as they did with regard to themselves.’ (Tafsir ibn Kathir). In the early period of the call for Truth, for those who came forward and embraced Islam, it was a discovery. The generation coming after them, regarded Islam as a legacy. It is this difference between discovery and legacy which raises the status of first group over that of the second group. Naturally, the second group is larger in number than the first group. In the Hereafter, there will be ordinary rewards for the second group while, for the first group, there will be royal rewards.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.