And if only they upheld [the law of] the Torah, the Gospel, (5:66)

﴿وَلَوْ أَنَّهُمْ أَقَامُوا التَّوْرَاةَ وَالْإِنجِيلَ وَمَا أُنزِلَ إِلَيْهِم مِّن رَّبِّهِمْ لَأَكَلُوا مِن فَوْقِهِمْ وَمِن تَحْتِ أَرْجُلِهِم ۚ مِّنْهُمْ أُمَّةٌ مُّقْتَصِدَةٌ ۖ وَكَثِيرٌ مِّنْهُمْ سَاءَ مَا يَعْمَلُونَ﴾
[ المائدة: 66]

5:66 And if only they upheld [the law of] the Torah, the Gospel, and what has been revealed to them from their Lord, they would have consumed [provision] from above them and from beneath their feet. Among them are a moderate community, but many of them - evil is that which they do.

If the Jews had practiced what was in the Torah, and the Christians practiced what was in the Gospel, and if all of them had practiced what was revealed to them in the Qur’ān, then I would have made the means of provision easy for them by sending down rain and growing vegetation.
From amongst the People of the Scripture are those who are moderate and firm on the truth; but the actions of many of them are evil, because they do not have faith in what was brought by Muhammad ( peace be upon him ).

And if only they had acted according to the Taurat (Torah), the Injeel (Gospel), and what has (now) been sent down to them from their Lord (the Quran), they would surely have gotten provision from above them and from underneath their feet. There are from among them people who are on the right course (i.e. they act on the revelation and believe in Prophet Muhammad SAW like 'Abdullah bin Salam), but many of them do evil deeds.

phonetic Transliteration

Walaw annahum aqamoo alttawrata waalinjeela wama onzila ilayhim min rabbihim laakaloo min fawqihim wamin tahti arjulihim minhum ommatun muqtasidatun wakatheerun minhum saa ma yaAAmaloona

Abdullah Yusuf Ali - Translation

If only they had stood fast by the Law, the Gospel, and all the revelation that was sent to them from their Lord, they would have enjoyed happiness from every side. There is from among them a party on the right course: but many of them follow a course that is evil.

Safi-ur-Rahman al-Mubarakpuri

And if only they had acted according to the Tawrah, the Injil, and what has (now) been sent down to them from their Lord (the Qur'an), they would surely have gotten provision from above them and from underneath their feet. And among them is a Muqtasid Ummah, but for most of them; evil is their work.

Page 119 English transliteration