The Messenger of Allah (peace and blessings be upon him) was twenty years old in the year of Ukaz

It is narrated from Sayyiduna Qays bin Makhramah (may Allah be pleased with him) that he said: The Messenger of Allah (peace and blessings be upon him) and I were both born in the "Year of the Elephant"; we were of the same age. Ibn Ishaq says that the Messenger of Allah (peace and blessings be upon him) was twenty years old at the time of (the war of) Ukaz.
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it.

Kindir bin Sa'id narrates from his father; he said: I performed Hajj in the time of Jahiliyyah, and I saw a man circling the House, reciting these rajaz verses: "My Lord, return my rider Muhammad to me; O my Lord, send him back to me and do me this favour." I asked: Who is this? The people told me: This is Abd al-Muttalib bin Hashim. He has sent his grandson Muhammad (peace and blessings be upon him) to search for his lost camels, and whatever task he sends him on, he always returns successful, but this time he has been late in coming. Only a little while had passed when Muhammad (peace and blessings be upon him) arrived with the camels. Abd al-Muttalib embraced him and said: O my dear son! I have been so anxious about you that I was never so distressed about anything. By Allah! I will never again send you on any errand (alone), nor will you ever be separated from me again.
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it. And the two Shaykhs have agreed, among the blessed names of the Messenger of Allah (peace and blessings be upon him), on Muhammad, Ahmad, al-Hashir, al-Aqib and al-Mahi.