Because it is a name derived from "increase" (ziyada); He is increased over all people in eloquence, knowledge, and courage. When He donned the sword, He was the bravest of men, and when He spoke, He was the most eloquent and articulate.

His father also named him: al-Samayda'

Abu Talib said on the day Quraysh reached a consensus to kill the Bani Hashim along with the Messenger of God—exalted be his glory:

And when I saw the people possessed no love, having severed the cord of ties and means;

Having allied with a people against us who are miserly, biting their fingertips in rage behind us;

We shall—by the life of God, the Grandeur of our Grandfather— grasp our swords by the shoulder-belts;

In the palm of a youth like a flame, a Samayda', a reliable brother, a protector of the reality, brave.

Abu Talib also named him: Zahira (A Helper/Manifest One)

Because He is manifest (zahir) over all things; His being named Zahira refers to the Outward and the Inward.

The Messenger of God named him: A Man (Rajulan)

Regarding his saying—exalted be his glory: "I shall indeed give the banner tomorrow to a man who loves God and His Messenger, and is loved by God and His Messenger." He intended by "a man" that He is the Perfect One in Himself. There was a consensus among the scholars of the Outward that the Messenger of God—exalted be his glory—had given it before that day, entrusting it first to the First and second to the Second, yet they returned defeated, as the report previously mentioned. Thus, He applied the feminine noun to them, supported by the words of the Almighty: {They invoke none instead of Him but females, and they invoke none but a rebellious devil whom God has cursed.