There is no basis for adding the word "al-murwas" to the hadith (The believer to the believer is like a building).

The Shaykh : And I say on this occasion that the hadith has become famous on the tongues of some preachers and exhorters with the addition of "al-murwas." The word "al-murwas" has no basis in the hadith; rather, the hadith is without it. A building is usually not anything but solid, so this statement is idle talk. First, it is said that in the hadith established from the Messenger (peace and blessings be upon him) without this word, one should add to it what the Messenger (peace and blessings be upon him) did not utter. And on this occasion, I also say that even if I lengthened my speech to you...