Tafsir Ibn Kathir (abridged)
Ismail ibn Kathir
Do not associate Anything in Worship with Allah
Addressing those who are responsible among this Ummah, Allah says, "Do not admit any partner into your worship of your Lord."
فَتَقْعُدَ مَذْمُومًا
(or you will sit down reproved,) meaning, because of associating others with Him.
مَّخْذُولاً
(forsaken.) means, because the Lord, may He be exalted, will not help you; He will leave you to the one whom you worshipped, and he has no power either to benefit or to harm, because the Only One Who has the power to benefit or to harm is Allah alone, with no partner or associate. Imam Ahmad reported that `Abdullah bin Mas`ud said: "The Messenger of Allah ﷺ said:
«مَنْ أَصَابَتْهُ فَاقَةٌ فَأَنْزَلَهَا بِالنَّاسِ لَمْ تُسَدَّ فَاقَتُهُ، وَمَنْ أَنْزَلَهَا بِاللهِ أَرْسَلَ اللهُ لَهُ بِالْغِنَى إِمَّا آجِلًا وَإِمَّا غِنىً عَاجِلًا»
(Whoever is afflicted with poverty and goes and asks people for help, will never get rid of his poverty, but if he asks Allah for help, then Allah will grant him the means of independence sooner or later.) This was also recorded by Abu Dawud and At-Tirmidhi, who said, "Hasan Sahih Gharib".
Ma'arif al-Qur'an
Mufti Muhammad Shafi
Sequence
Previous verses mentioned some conditions attached to the acceptance of deeds. One of the conditions required that no deed is accepted unless it comes with 'Iman (faith, belief) and is in accordance with Shari` ah (Law) and Sunnah (sayings and deeds of the Prophet ﷺ). In the present verses, instructions regarding some of such deeds have been given. These are rules set by the Shari'ah of Islam. Their compliance brings success in the Hereafter and their contravention, ruin. And since the most important of these conditions is that of 'Iman, therefore, the very first injunction given here was that of belief in the Oneness of Allah (tauhid). After that come injunctions relating to the rights of the servants of Allah (huquq al-` ibad).
Be it in this world or in the Hereafter, success results from availing of the opportunities provided by God. For those who have made success in the life Hereafter the goal of their lives, God has made such dispositions as will facilitate the spiritual journey leading to that success in the next world. One can see that in this world some people are ahead of others, while some are lagging behind. Some have more and some have less. These are ways of telling us in the language of symbols, that there is no limit to opportunities in this world of God. The harder one works the more one achieves. Similarly, the more one is involved in Hereafter-oriented activities, the greater the reward one will receive in the Hereafter. Furthermore, whatever one receives in the next world will be eternal, while whatever one receives in this world will be ephemeral in nature.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.