The claim is that the word "yubbayyin" in 5:19 lays a duty on the messenger to explain the Quran that was revealed to him. They add that the hadith of Prophet Muhammad explains the Quran and is, therefore, a legitimate source of Islam. This is what surah 5 verse 19 says:
Surah 5 Verse 19
Literal – Word by word
O People (of) the Book! Surely has come to you Our Messenger, he makes clear to you [on] (after) an interval (of cessat of the Messengers, lest you say "Not (has) come to us any bearer of glad tidings and not a warner." But surely has come to you a bearer of glad tidings and a warner. And Allah (is) on everything All-Powerful.
If we accept the above interpretation of 5:19, we will immediately run into what seems like a Quranic contradiction. To demonstrate this, we need to read the following verses:
16 - Do not move your tongue with it (O Muhammad) to hasten it.
17 - Indeed, upon Us is its collection and its recitation.
18 - Once We recite it, you shall follow such a recitation.
19 - Then upon Us is its explanation.
The underlined words in verse 19 assert it is God, and not the messenger, who teaches and explains the meaning of the Quran in the hearts of the guided ones. The same truth that it is God who explains the Quran is given in the following words:
Al-Rahman taught the Quran. 55:1-2
Further confirmation of the above is found in the Quranic assurance that the only duty of the messenger is to deliver the message of God (Quran) to the people:
Surah 5 Verse 99
“The sole duty of the messenger is the delivery, and God knows what you reveal and what you conceal.”
Surah 5 Verse 67
“O you messenger convey what was brought down to you from your Lord. If you do not, then you have not delivered His message.”
As we know, there are no contradictions in the Holy Quran. The apparent contradiction can be eliminated when we use Quranic evidence to determine the correct meaning of the command to "yubbayyin" in 5:19.
The key verse which provides us with this clarification is the following:
God took a covenant from those who received the Scripture: "You shall 'tubayinunnahu' (make it clear) to the people, and not conceal it." 3:187
The words in 2:213 tell us that God revealed the Scripture to His prophets. Therefore, the words "those who received the Scripture" in 3:187 refer to the prophets of God, one of whom is the prophet Muhammad.
The importance of 3:187 is that not only does it use the same verb "yubbayyin", but it also provides us with the antonym of "yubbayyin". The antonym given by God in 3:187 for "yubbayyin" is "conceal".
And so to attain the correct context of "yubbayyin" as used in 5:19 and also 3:187, we need to perform a reverse process and determine the antonym of the word "conceal".
The antonym of (conceal) is: reveal, disclose or make clear.
It becomes evident that in the context of 5:19 and 3:187, God is commanding the messenger to make clear to the people what was revealed to him from God and not to conceal any of it.
However, the task of explaining the Quran in the hearts of people lies on God (75:19).
Following this Quran analysis and clarification, all the verses make perfect sense and no contradiction lies within them.
Please verify everything you read with the Quran itself.
Peace and Respect!
1 - Wikipedia.org
2 - quran-islam.org