Allah's Signs displayed during Badr, And throwing Sand in the Eyes of the Disbelievers
Allah states that He creates the actions that the servants perform and that whatever good actions they take, it is He Who should be praised for them, for He directed and helped them perform these actions. Allah said,
(You killed them not, but Allah killed them.) meaning, it is not because of your power and strength that you killed the pagans, who were many while you were few. Rather, it is He Who gave you victory over them, just as He said in another Ayah,
(Truly, Allah has given you victory on many battlefields, and on the day of Hunayn when you rejoiced at your great number, but it availed you naught and the earth, vast as it is, was straitened for you, then you turned back in flight.) 9:25
Allah, the Exalted and Ever High, states that victory does not depend on numbers or collecting weapons and shields. Rather, victory is from Him, Exalted He is.
(How often has a small group overcome a mighty host by Allah's leave'' And Allah is with the patient.) 2:249
Allah then mentioned the handful of sand that His Prophet threw at the disbelievers during the day of Badr, when he went out of his bunker. While in the bunker, the Prophet invoked Allah humbly and expressing his neediness before Allah. He then threw a handful of sand at the disbelievers and said,
(Humiliated be their faces.) He then commanded his Companions to start fighting with sincerity and they did. Allah made this handful of sand enter the eyes of the idolators, each one of them were struck by some of it and it distracted them making each of them busy. Allah said,
(that He might test the believers by a fair trial from Him. ) "So that the believers know Allah's favor for them by giving them victory over their enemy, even though their enemy was numerous, while they were few. They should thus know His right and express gratitude for His favor on them.'' Similar was said by Ibn Jarir. It is stated in a Hadith,
«وَكُلَّ بَلَاءٍ حَسَنٍ أَبْلَانَا»
(Every trail (from Allah) is a favor for us.)
Allah said next,
إِنَّ اللَّهَ سَمِيعٌ عَلِيمٌ
(Verily, Allah is All-Hearer, All-Knower.)
Allah hears the supplication and knows those who deserve help and triumph. Allah said,
(This (is the fact) and surely Allah weakens the deceitful plots of the disbelievers.) This is more good news, aside from the victory that the believers gained. Allah informed them that He will weaken the plots of the disbelievers in the future, degrade them and make everything they have perish and be destroyed, all praise and thanks are due to Allah.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
This refers to an event that happened during the Battle of Badr. After single bouts, when a general fight was going to ensue, the Holy Prophet took a handful of sand and threw it towards the army of the disbelievers, saying, "May their faces be scorched." At the same time he made a gesture and the Muslims attacked the disbelievers in a body.
This refers to the prayer that was offered by the Quraish at the Ka'abah before they marched for the fight. The mushriks held the curtains of the Ka`abah and prayed: "O Allah! grant victory to the better of the two parties." Abu Jahl particularly invoked Allah's decision, saying, "O God! grant victory to that party which is in the right, and disgrace that one which is the aggressor. "
Accordingly Allah gave His decision and granted their prayer to the letter by giving a signal victory to the Muslims to show that they were the better of the two parties and were in the right.