Allah says,

[أَوَلَمْ يَرَوْا إِلَى الطَّيْرِ فَوْقَهُمْ صَــفَّـتٍ وَيَقْبِضْنَ]

(Do they not see the birds above them, spreading out their wings and folding them in) meaning, sometimes they spread their wings out in the wind (gliding) and other times they gather and spread (flapping) the wings in flight

[مَا يُمْسِكُهُنَّ]

(None upholds them) meaning, in the air,

[إِلاَّ الرَّحْمَـنُ]

(except the Most Gracious.) meaning, Allah holds them up in the air by subjecting the air to them out of His mercy and His gentleness.

[إِنَّهُ بِكُلِّ شَىْءٍ بَصِيرٌ]

(Verily, He is the All-Seer of everything.) means, with what is beneficial and suitable for all of His creatures. This is similar to His statement,

[أَلَمْ يَرَوْاْ إِلَى الطَّيْرِ مُسَخَّرَتٍ فِى جَوِّ السَّمَآءِ مَا يُمْسِكُهُنَّ إِلاَّ اللَّهُ إِنَّ فِى ذلِكَ لآيَـتٍ لِّقَوْمٍ يُؤْمِنُونَ ]

(Do they not see the birds held in the midst of the sky None upholds them but Allah. Verily, in this are clear Ayat for people who believe.) [24:79]

[أَمَّنْ هَـذَا الَّذِى هُوَ جُندٌ لَّكُمْ يَنصُرُكُمْ مِّن دُونِ الرَّحْمَـنِ إِنِ الْكَـفِرُونَ إِلاَّ فِى غُرُورٍ - أَمَّنْ هَـذَا الَّذِى يَرْزُقُكُمْ إِنْ أَمْسَكَ رِزْقَهُ بَل لَّجُّواْ فِى عُتُوٍّ وَنُفُورٍ - أَفَمَن يَمْشِى مُكِبّاً عَلَى وَجْهِهِ أَهْدَى أَمَّن يَمْشِى سَوِيّاً عَلَى صِرَطٍ مُّسْتَقِيمٍ - قُلْ هُوَ الَّذِى أَنشَأَكُمْ وَجَعَلَ لَكُمُ السَّمْعَ وَالاٌّبْصَـرَ وَالاٌّفْئِدَةَ قَلِيلاً مَّا تَشْكُرُونَ - قُلْ هُوَ الَّذِى ذَرَأَكُمْ فِى الاٌّرْضِ وَإِلَيْهِ تُحْشَرُونَ وَيَقُولُونَ مَتَى هَـذَا الْوَعْدُ إِن كُنتُمْ صَـدِقِينَ قُلْ إِنَّمَا الْعِلْمُ عِندَ اللَّهِ وَإِنَّمَآ أَنَاْ نَذِيرٌ مُّبِينٌ فَلَمَّا رَأَوْهُ زُلْفَةً سِيئَتْ وُجُوهُ الَّذِينَ كَفَرُواْ وَقِيلَ هَـذَا الَّذِى كُنتُم بِهِ تَدَّعُونَ ]

(20. Who is it besides the Most Gracious that can be an army to you to help you The disbelievers are in nothing but delusion.) (21. Who is it that can provide for you if He should withhold His provision Nay, but they continue to be in pride, and flee.) (22. Is he who walks prone on his face, more rightly guided, or he who walks upright on a straight path) (23. Say: "It is He Who has created you, and endowed you with hearing and seeing, and hearts. Little thanks you give.'') (24. Say: "It is He Who has created you on the earth, and to Him shall you be gathered.'') (25. They say: "When will this promise come to pass, if you are telling the truth'') (26. Say: "The knowledge is with Allah only, and I am only a plain warner.'') (27. But when they will see it approaching, the faces of those who disbelieve will be sad and grievous, and it will be said: "This is what you were calling for!'')