The Qur’an sums up the scene of the fight between Saul and Goliath and their soldiers in these words: (So they defeated them by permission of Allah,) i.e. by the order of Allah (swt) because they were patient, they were tested and passed. Thus, Allah (swt) filled their hearts with patience, planted their feet firmly, and made them victorious over Goliath and his soldiers.

(… وَقَتَلَ دَاوُودُ جَالُوتَ..  ) (...and David killed Goliath…): Was Goliath killed by Saul or David? The Holy Qur’an says Goliath was killed by David. Here is the first time David (PBUH) is mentioned in the Qur’an and in the history of the Children of Israel. Yet, the Qur’an does not clarify where David was. It can be concluded that he was a soldier in the army of Goliath among the believers of the Children of Israel. David was younger to Goliath, but he’s the one who killed the strong and great Goliath. So, this marks the beginning of the era of David who subsequently became a prophet and a king with whom mountains and birds used to repeat Allah’s praises, and Allah (swt) made iron pliable for him:

{ وَلَقَدْ آتَيْنَا دَاوُودَ مِنَّا فَضْلًا ۖ يَا جِبَالُ أَوِّبِي مَعَهُ وَالطَّيْرَ ۖ وَأَلَنَّا لَهُ الْحَدِيدَ }

(And We certainly gave David from Us bounty. [We said], “O mountains, repeat [Our] praises with him, and the birds [as well].” And We made pliable for him iron,.)  (Saba: 10)

After David comes Solomon, his son. Anyway, here we have the name of young David who was in the army of Saul and killed Goliath:

(… وَآتَاهُ اللَّهُ الْمُلْكَ وَالْحِكْمَةَ وَعَلَّمَهُ مِمَّا يَشَاءُ..  ) (...and Allah gave him the kingship and prophethood and taught him from that which He willed….): Allah (swt) gave him the kingship after he was raised up on faith, was patient, fought, and killed Goliath so David became the prophet king:

 {وَلَقَدْ آتَيْنَا دَاوُودَ وَسُلَيْمَانَ عِلْمًا ۖ وَقَالَا الْحَمْدُ لِلَّهِ الَّذِي فَضَّلَنَا عَلَىٰ كَثِيرٍ مِّنْ عِبَادِهِ الْمُؤْمِنِينَ }

(And We had certainly given to David and Solomon knowledge, and they said, “Praise [is due] to Allah, who has favored us over many of His believing servants.”.)  (An-Naml: 10)

Allah did not only give David the kingship but also wisdom (knowledge). Whenever we hear wisdom, we immediately remember the Sunnah of Prophet Muhammad (saws) as well as the supplication of Abraham (PBUH), the grandfather of all prophets, including David and Prophet Muhammad (saws), along with his son Ismael (PBUH) when they were raising the foundation of the House:

 إِذْ يَرْفَعُ إِبْرَاهِيمُ الْقَوَاعِدَ مِنَ الْبَيْتِ وَإِسْمَاعِيلُ رَبَّنَا تَقَبَّلْ مِنَّا ۖ إِنَّكَ أَنتَ السَّمِيعُ الْعَلِيمُ * رَبَّنَا وَاجْعَلْنَا مُسْلِمَيْنِ لَكَ وَمِن ذُرِّيَّتِنَا أُمَّةً مُّسْلِمَةً لَّكَ وَأَرِنَا مَنَاسِكَنَا وَتُبْ عَلَيْنَا ۖ إِنَّكَ أَنتَ التَّوَّابُ الرَّحِيمُ * رَبَّنَا وَابْعَثْ فِيهِمْ رَسُولًا مِّنْهُمْ يَتْلُو عَلَيْهِمْ آيَاتِكَ وَيُعَلِّمُهُمُ الْكِتَابَ وَالْحِكْمَةَ وَيُزَكِّيهِمْ ۚ إِنَّكَ أَنتَ الْعَزِيزُ الْحَكِيمُ

(And [mention] when Abraham was raising the foundations of the House and [with him] Ishmael, [saying], “Our Lord, accept [this] from us. Indeed You are the Hearing, the Knowing. % Our Lord, and make us Muslims [in submission] to You and from our descendants a Muslim nation [in submission] to You. And show us our rites and accept our repentance. Indeed, You are the Accepting of repentance, the Merciful.)  (Al-Baqara: 127-129) And

{ وَاذْكُرْنَ مَا يُتْلَىٰ فِي بُيُوتِكُنَّ مِنْ آيَاتِ اللَّهِ وَالْحِكْمَةِ ۚ إِنَّ اللَّهَ كَانَ لَطِيفًا خَبِيرًا }

(And remember what is recited in your houses of the verses of Allah and wisdom. Indeed, Allah is ever Subtle and Acquainted [with all things].)  (Al-Ahzab: 34)

In sum, Allah (swt) gave David the kingship and wisdom, taught him whatever He wants; made the jinn and birds under his control, and made iron pliable for him.

(… وَلَوْلَا دَفْعُ اللَّهِ النَّاسَ بَعْضَهُم بِبَعْضٍ لَّفَسَدَتِ الْأَرْضُ..  ) (...And if it were not for Allah checking [some] people by means of others, the earth would have been corrupted….): There is a verse similar to this one in the Sura of (Al-Hajj) which reads:

 { وَلَوْلَا دَفْعُ اللَّهِ النَّاسَ بَعْضَهُم بِبَعْضٍ لَّهُدِّمَتْ صَوَامِعُ وَبِيَعٌ وَصَلَوَاتٌ وَمَسَاجِدُ يُذْكَرُ فِيهَا اسْمُ اللَّهِ كَثِيرًا }

(And were it not that Allah checks the people, some by means of others, there would have been demolished monasteries, churches, synagogues, and mosques in which the name of Allah is much mentioned..)  (Al-Hajj: 40)

What is the meaning of ‘checking?’ it means hindering. People are different but have the freedom of choice between belief or disbelief; justice or oppression; good doing or killing; the good or the bad; the right or the wrong. However, Allah (swt) checks (repels) these by means of those: repels injustice by means of justice and the wrong by means of the right, or else earth would have been corrupted. This is rule of repelling that is due to differences and freedom of choice. Had not the freedom of choice been there wrong doing would not have there on earth, and people would have been doing what Allah (swt) orders and as obeying as the angles. Therefore checking (repelling) is a universal rule:

(… وَلَوْلَا دَفْعُ اللَّهِ النَّاسَ بَعْضَهُم بِبَعْضٍ لَّفَسَدَتِ الْأَرْضُ..  ) (...And if it were not for Allah checking [some] people by means of others, the earth would have been corrupted….): By means of what is in the hands of people rather than what is not in their hands. Why? Because no corrupt person can prevent the sun from rising, for example. It is not in their hands. Corruption is through what is in the hands of people:

 {ظَهَرَ الْفَسَادُ فِي الْبَرِّ وَالْبَحْرِ بِمَا كَسَبَتْ أَيْدِي النَّاسِ لِيُذِيقَهُم بَعْضَ الَّذِي عَمِلُوا لَعَلَّهُمْ يَرْجِعُونَ }

(Corruption has appeared throughout the land and sea by [reason of] what the hands of people have earned so He may let them taste part of [the consequence of] what they have done that perhaps they will return [to righteousness].)  (Ar-Room: 41)

Uprightness is created by Allah (swt) while corruption is human-made. Moreover, every kind of corruption in the creation of Allah (swt) is created by Allah (swt) but not made by Him. In short, we have to consider one thing: Allah (swt) has granted many favors like the sun, the moon, fresh air, plants, safety, food … etc. to all people. Yet, corruption happens when favors is met with disobedience; whereas uprightness takes place when favors are met with gratitude.

(… وَلَٰكِنَّ اللَّهَ ذُو فَضْلٍ عَلَى الْعَالَمِينَ ) (….but Allah is full of bounty to the worlds.): Allah (swt), then, is full of bounty, and bounty is above justice. He is full of bounty to people.