هَلُمَّ إِلَيْنَا
(Come here towards us,) meaning, come to where we are in the shade and enjoying fruits. But in spite of that,
وَلاَ يَأْتُونَ الْبَأْسَ إِلاَّ قَلِيلاً
أَشِحَّةً عَلَيْكُمْ
(they come not to the battle except a little, being miserly towards you.) i.e., `they are mean and have no love or mercy towards you.' As-Suddi said:
أَشِحَّةً عَلَيْكُمْ
(Being miserly towards you.) means, with the booty.
فَإِذَا جَآءَ الْخَوْفُ رَأَيْتَهُمْ يَنظُرُونَ إِلَيْكَ تَدورُ أَعْيُنُهُمْ كَالَّذِى يُغْشَى عَلَيْهِ مِنَ الْمَوْتِ
(Then when fear comes, you will see them looking to you, their eyes revolving like one over whom hovers death;) means, because of the intensity of their fear and terror; this is how afraid these cowards are of fighting.
فَإِذَا ذَهَبَ الْخَوْفُ سَلَقُوكُم بِأَلْسِنَةٍ حِدَادٍ
(but when the fear departs, they will smite you with sharp tongues,) means, when security is restored, they will speak eloquently and nicely, claiming that they were the bravest and most chivalrous of men, but they are lying. Ibn `Abbas, may Allah be pleased with him, said:
سَلَقُوكُم
(they will smite you) means, 'they will start to talk about you.\” Qatadah said: 'But when it comes to the booty, the most miserly of people and the worst to have to share the booty with are those who say, `Give us, give us, we were there with you,' but during battle they were the most cowardly and the most likely to fail to support the truth.\” They are miserly towards good, meaning that there is no goodness in them, for they have combined cowardice with lies and little good. Allah says:
أوْلَـئِكَ لَمْ يُؤْمِنُواْ فَأَحْبَطَ اللَّهُ أَعْمَـلَهُمْ وَكَانَ ذَلِكَ عَلَى اللَّهِ يَسِيراً
(Such have not believed. Therefore Allah makes their deeds fruitless and that is ever easy for Allah.)
The second state mentioned here is that of the hypocrites for they had started saying that the promises of Allah and His Rasul ﷺ were a web of deception: إِذْ يَقُولُ الْمُنَافِقُونَ وَالَّذِينَ فِي قُلُوبِهِم مَّرَضٌ مَّا وَعَدَنَا اللَّـهُ وَرَسُولُهُ إِلَّا غُرُورًا (And (remember) when the hypocrites and those having malady in their hearts were saying, "Allah and His messenger did not promise us but deceitfully; -12). This was an externalized demonstration of their inner disbelief. Onward from here, mention has been made of two groups of hypocrites who were practically a part of the Jihad effort along with Muslims, though outwardly only. One of the two groups started running without any permission saying: وَإِذْ قَالَت طَّائِفَةٌ مِّنْهُمْ يَا أَهْلَ يَثْرِبَ لَا مُقَامَ لَكُمْ فَارْجِعُوا (and when a group of them said, "0 people of Yathrib (Madinah), there is no place for you to stay; so go back. - 13" And the other group requested the permission of the Holy Prophet ﷺ to go back on the basis of false excuses. Their conduct has been mentioned as: وَيَسْتَأْذِنُ فَرِيقٌ مِّنْهُمُ النَّبِيَّ يَقُولُونَ إِنَّ بُيُوتَنَا عَوْرَةٌ (And a group of them was seeking permission (to leave) from the prophet, saying, "In fact our homes are vulnerable," while they were not vulnerable - 13). Thus, the Qur'an exposed the hollowness of their excuses as a pack of lies. The truth of the matter was no more than that they intended to run from the battlefront:إِن يُرِيدُونَ إِلَّا فِرَارًا (They wanted nothing but to escape - 13). Taken up in the next several verses is their mischief-making and enmity with Muslims following which their sad end has been pointed out.
Continue reading the tafsir of ayahs 13–27 Realizing that the situation at the battle of Ahzab, was fraught with danger, the hypocrites were terrified and started exploring ways and means of fleeing. But the true and faithful ones firmly placed their reliance on God. They knew very well that God was before them and He was behind them. To run away from the danger of the enemies of Islam amounted to placing oneself in danger of God’s chastisement, which was by far the greater hazard. They firmly believed that if they were steadfast in the face of their enemies, God’s help would be forthcoming. On the other hand, they knew that if they fled the Islamic front, they would not be able to save themselves from either destruction in this world or God’s terrible scourge in the Hereafter.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.