According to the majority of Shia public and many Shia scholars as well, the Prophet (s) would not do anything without “Wahi” (revelation), and he (s) would not speak but only when Allah (swt) revealed to him.
This claim is backed with the verse of the Quran, 53:3-4:
(4) وَمَا يَنْطِقُ عَنِ الْهَوَىٰ(3) إِنْ هُوَ إِلَّا وَحْيٌ يُوحَىٰ
Nor does he speak out of desire (3) It is nothing but revelation that is revealed.(4)
Well, this is a flawed understanding, since this can be easily refuted by the Quran itself, by simply pondering over the Quran.
Refutation:
It would be illogical to imagine that first Allah (swt) reveals to Rasulallah (s) to do or say something, and then contradict Himself by questioning the Prophet (s) about the same thing that He (swt) had revealed.
Verse 1: Surah Tahreem, 66:1
يَا أَيُّهَا النَّبِيُّ لِمَ تُحَرِّمُ مَا أَحَلَّ اللَّهُ لَكَ ۖ تَبْتَغِي مَرْضَاتَ أَزْوَاجِكَ ۚ وَاللَّهُ {1}غَفُورٌ رَحِيمٌ
O Prophet! why do you forbid (yourself) that which Allah has made lawful for you; you seek to please your wives; and Allah is Forgiving, Merciful.
Many Shias know the occasion of revelation of this Ayat. In Brief, two wives of the Prophet (s) conspired against him and planned to annoy the Prophet (s) by telling him that his mouth smells bad because of the honey drink he had at another wife’s house. Because of the high morals of Rasulallah (s), to please his wives, he said that he will not have that honey drink again. This is when Allah (swt) revealed this verse “O Prophet! why do you forbid (yourself) that which Allah has made lawful for you; you seek to please your wives; and Allah is Forgiving, Merciful.”
Question: If we assume that Rasulallah (saww) only speaks or does something when Allah (swt) reveals it to him, then that would mean that when Rasulallah (saww) said “I will not have that honey drink again”, this was also a revelation from Allah (swt). If this is the case, then why did Allah (swt) question the Prophet (saww) “O Prophet! why do you forbid (yourself) that which Allah has made lawful for you….”, when in fact it was Allah (swt) Himself in the first place who revealed to the Prophet (saww) to forbid this drink upon himself (as per the flawed understanding of majority of Shias).
Verse 2: Surah Anfaal, 8:67-69
مَا كَانَ لِنَبِيٍّ أَنْ يَكُونَ لَهُ أَسْرَىٰ حَتَّىٰ يُثْخِنَ فِي الْأَرْضِ ۚ تُرِيدُونَ عَرَضَ الدُّنْيَا {67}وَاللَّهُ يُرِيدُ الْآخِرَةَ ۗ وَاللَّهُ عَزِيزٌ حَكِيمٌ
It is not fit for a prophet that he should take captives unless he has fought and triumphed in the land; you desire the frail goods of this world, while Allah desires (for you) the hereafter; and Allah is Mighty, Wise.
لَوْلَا كِتَابٌ مِنَ اللَّهِ سَبَقَ لَمَسَّكُمْ فِيمَا أَخَذْتُمْ عَذَابٌ عَظِيمٌ {68}
Had it not been for a previous ordainment from Allah, a severe penalty would have reached you for the (ransom) that ye took.
فَكُلُوا مِمَّا غَنِمْتُمْ حَلَالًا طَيِّبًا ۚ وَاتَّقُوا اللَّهَ ۚ إِنَّ اللَّهَ غَفُورٌ رَحِيمٌ {69}
But (now) enjoy what ye took in war, lawful and good: but fear Allah: for Allah is Oft-forgiving, Most Merciful.
In the battle of Badr, on the orders of the Prophet (s), the companions took some captives, but Allah (swt) did not like it, so he corrected the Prophet (s) and informed him that this is not right.
Now how is it possible, that first Allah (swt) himself asked the Prophet (s) to take captive and ransom, and after the Prophet (saw) did that, Allah (swt) reveals “It is not fit for a prophet that he should take captives unless he has fought and triumphed in the land….”?
Verse 3: Surah Tawba, 9:43
عَفَا اللَّهُ عَنْكَ لِمَ أَذِنْتَ لَهُمْ حَتَّىٰ يَتَبَيَّنَ لَكَ الَّذِينَ صَدَقُوا وَتَعْلَمَ الْكَاذِبِينَ {43}
Allah forgive you! Why did you give them leave until those who spoke the truth had become manifest to you and you had known the liars?
Before the Battle of Tabuk, some hypocrites (munafiqoon) came to the Prophet (s) and asked him if they can stay back and not participate in the battle, so the Prophet (s) gave them permission. After that the following verse was revealed “Allah forgive you! Why did you give them leave until those who spoke the truth had become manifest to you and you had known the liars?”
How is it possible, that first Allah (swt) revealed to Rasulallah (saww) to give the hypocrites permission to stay back, and when Rasulallah (saww) did that, then Allah (swt) says “..Why did you give them leave…”?
Clearly, all this is illogical, therefore we cannot accept the fact that the Prophet (saww) only speaks or acts when Allah (swt) reveals it to him. In his normal life the Prophet (saww) speaks without revelation, the verse of Surah Najm 53:3-4 only refers to the Quran.
إِنْ هُوَ إِلَّا وَحْيٌ يُوحَىٰ
The “هُو” (it) refers to the Quran in this verse.
So the verse is basically saying that the Quran is not something made up by the Prophet (saww), rather it is nothing but revelation from Allah (swt).