Allah tells us that He chooses Messengers from His angels as He wills by His law and decree, and He chooses Messengers from mankind to convey His Message.

﴿إِنَّ اللَّهَ سَمِيعٌ بَصِيرٌ﴾

(Verily, Allah is All-Hearer, All-Seer.) means, He hears all that His servants say, and He sees them and knows who among them is deserving of that, as He says:

﴿اللَّهُ أَعْلَمُ حَيْثُ يَجْعَلُ رِسَالَتَهُ﴾

(Allah knows best with whom to place His Message) ﴿6:124﴾

﴿يَعْلَمُ مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ وَإِلَى اللَّهِ تُرْجَعُ الاٍّمُورُ ﴾

(He knows what is before them, and what is behind them. And to Allah return all matters.) He knows what will happen to His Messengers and the Message He sent them with, for none of their affairs are hidden from Him. He says:

﴿عَـلِمُ الْغَيْبِ فَلاَ يُظْهِرُ عَلَى غَيْبِهِ أَحَداً ﴾

("The All-Knower of the Ghayb (Unseen), and He reveals to none His Ghayb.'')﴿72:26﴾ until His saying;

﴿وَأَحْصَى كُلَّ شَىْءٍ عَدَداً﴾

(and He keeps count of all things.) ﴿72:28﴾ So He, may He be glorified, is guarding them, and is Witness to what is said about them. He is protecting them and supporting them.

﴿يَـأَيُّهَا الرَّسُولُ بَلِّغْ مَآ أُنزِلَ إِلَيْكَ مِن رَّبِّكَ وَإِن لَّمْ تَفْعَلْ فَمَا بَلَّغْتَ رِسَالَتَهُ وَاللَّهُ يَعْصِمُكَ مِنَ النَّاسِ﴾

(O Messenger! Proclaim which has been sent down to you from your Lord. And if you do not, then you have not conveyed His Message. Allah will protect you from mankind) ﴿5:67﴾.

﴿يأَيُّهَا الَّذِينَ ءَامَنُواْ ارْكَعُواْ وَاسْجُدُواْ وَاعْبُدُواْ رَبَّكُمْ وَافْعَلُواْ الْخَيْرَ لَعَلَّكُمْ تُفْلِحُونَ - وَجَـهِدُوا فِى اللَّهِ حَقَّ جِهَـدِهِ هُوَ اجْتَبَـكُمْ وَمَا جَعَلَ عَلَيْكمْ فِى الدِّينِ مِنْ حَرَجٍ مِّلَّةَ أَبِيكُمْ إِبْرَهِيمَ هُوَ سَمَّـكُمُ الْمُسْلِمِينَ مِن قَبْلُ وَفِى هَـذَا لِيَكُونَ الرَّسُولُ شَهِيداً عَلَيْكُمْ وَتَكُونُواْ شُهَدَآءَ عَلَى النَّاسِ فَأَقِيمُواْ الصَّلَوةَ وَءَاتُواْ الزَّكَـوةَ وَاعْتَصِمُواْ بِاللَّهِ هُوَ مَوْلَـكُمْ فَنِعْمَ الْمَوْلَى وَنِعْمَ النَّصِيرُ ﴾

(77. O you who believe! Bow down, and prostrate yourselves, and worship your Lord and do good that you may be successful.) (78. And strive hard in Allah's cause as you ought to strive. He has chosen you, and has not laid upon you in religion any hardship: it is the religion of your father Ibrahim. He has named you Muslims both before and in this (Qur'an), that the Messenger may be a witness over you and you be witnesses over mankind! So, perform the Salah, give the Zakah and hold fast to Allah. He is your Mawla, what an Excellent Mawla and what an Excellent Helper!)