Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: When the Prophet (peace and blessings be upon him) and his household were in the Shi'b, my father (Abbas (may Allah be pleased with him)) came to the Prophet (peace and blessings be upon him) and said: O Muhammad! I think Umm al-Fadl has become pregnant. He (peace and blessings be upon him) said: "Perhaps Allah will cool our eyes with a son." So I was brought to the Prophet (peace and blessings be upon him) while I was wrapped in my cloth, and he did tahnik for me (chewed something and rubbed it on my palate). Mujahid said: We know of no one other than him (Sayyiduna Ibn Abbas (may Allah be pleased with them both)) who received tahnik with the saliva of prophethood.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10520