All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
At-Tayyib is one of the Names of Allaah, the Exalted. This Name was reported in many Hadeeths. For example, it was reported on the authority of Abu Hurayrah that the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said that Allaah is Tayyib (Good) and that he accepts only what is good. [Muslim]
On the other hand, it should be known that the Quran and the Sunnah do not include all the Names of Allaah the Exalted. There are other Names that He, the Almighty, has kept hidden and He alone knows. This fact is established in the Hadeeth which was reported on the authority of Ibn Mas‘ood that the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, used to say in his supplication: "'As’aluka bikulli-Ismin Huwa-lak Samayyita bihi Nafsak, 'aww-'anzaltahu fi-kitaabik, ‘aww-‘alamtahu ahadan min khalqik, 'aww-'ista’tharta bihi fi-‘ilmi al-ghaybi ‘indak….. (I implore You by means of all the Names You attribute to Yourself, or taught to any of Your creatures, or mentioned in Your Book, or kept hidden in the Unseen…..)" [Ahmad, Al-Haakim and Ibn Hibaan: (Saheeh)]
Allaah Knows best.