Whoever tells that Muhammad concealed part of what was revealed to him, is a liar, for Allah says:-- "O Apostle (Muhammad)! Proclaim (the Message) which has been sent down to you from your Lord." (5.67)
أَنَّ مُحَمَّدًا ﷺ كَتَمَ شَيْئًا مِمَّا أُنْزِلَ عَلَيْهِ فَقَدْ كَذَبَ وَاللَّهُ يَقُولُ {يَا أَيُّهَا الرَّسُولُ بَلِّغْ مَا أُنْزِلَ إِلَيْكَ} الآيَةَ