In the vision of Islam, they are known as "essentials" because they are considered essential to human welfare. In conclude, if someone were to ask, what is the core of Islam in the fewest possible words, the answer would be, "it is within the word Islam itself: to serve, worship, and lovingly submit to God."
بِسْمِ اللهِ الرَّحْمٰنِ الرَّحِيْمِ
In the Name of Allah, the Most Gracious, the Most Merciful.
يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تُلْهِكُمْ أَمْوَالُكُمْ وَلَا أَوْلَادُكُمْ عَن ذِكْرِ اللَّهِ وَمَن يَفْعَلْ ذَلِكَ فَأُوْلَئِكَ هُمُ الْخَاسِرُونَ
O you who believe! Let neither your properties nor your children divert you from the remembrance of Allah. And whoever does that is the loser. (Surah Al-Munafiqun 63:9)
وَأَنفِقُوا مِن مَّا رَزَقْنَاكُم مِّن قَبْلِ أَن يَأْتِيَ أَحَدَكُمُ الْمَوْتُ فَيَقُولَ رَبِّ لَوْلَا أَخَّرْتَنِي إِلَى أَجَلٍ قَرِيبٍ فَأَصَّدَّقَ وَأَكُن مِّنَ الصَّالِحِينَ
And expend of that with which We have provided you before death comes to any of you when he says: "My Lord! If only You would give me respite for a little while, then I should give alms and be amongst the righteous". (Surah Al-Munafiqun 6363:10)
مَثَلُ الَّذِينَ يُنْفِقُونَ أَمْوَالَهُمْ فِي سَبِيلِ اللَّهِ كَمَثَلِ حَبَّةٍ أَنْبَتَتْ سَبْعَ سَنَابِلَ فِي كُلِّ سُنْبُلَةٍ مِائَةُ حَبَّةٍ ۗ وَاللَّهُ يُضَاعِفُ لِمَنْ يَشَاءُ ۗ وَاللَّهُ وَاسِعٌ عَلِيمٌ
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. [Al-Baqarah 2:261]
Abu Huraira (RadhiAllahu 'anhu) reported: Allah's Messenger ﷺ as saying: When a man dies, his acts come to an end, but three, recurring charity or knowledge (by which people) benefit, or a pious son, who prays for him (for the deceased). [Sahih Muslim – Book 13 – Hadith 4005]
كُنۡتُمۡ خَيۡرَ اُمَّةٍ اُخۡرِجَتۡ لِلنَّاسِ تَاۡمُرُوۡنَ بِالۡمَعۡرُوۡفِ وَتَنۡهَوۡنَ عَنِ الۡمُنۡكَرِ وَتُؤۡمِنُوۡنَ بِاللّٰهِؕ وَلَوۡ اٰمَنَ اَهۡلُ الۡكِتٰبِ لَڪَانَ خَيۡرًا لَّهُمۡؕ مِنۡهُمُ الۡمُؤۡمِنُوۡنَ وَاَكۡثَرُهُمُ الۡفٰسِقُوۡنَ
Ye are the best of peoples evolved for mankind enjoining what is right forbidding what is wrong and believing in Allah. If only the People of the Book had faith it were best for them; among them are some who have faith but most of them are perverted transgressors. Surah Al-i'Imran 3: 110