From the sermon of Prophet Muhammad (صلى الله عليه وآله) at Ghadir as narrated from Imam Muhammad Baqir (عليه السلام):

ألا إن خاتم الائمة منا القائم المهدي

Verily, the Seal of the Imams from among us is the Qaim, the Mahdi.

ألا إنه الظاهر على الدين

Verily, he is the one who will be victorious over all [other] Religion.

ألا إنه المنتقم من الظالمين

Verily, he is the avenger of the oppressors.

ألا إنه فاتح الحصون وهادمها

Verily, he is the conqueror of fortresses and their demolisher.

ألا إنه قاتل كل قبيلة من أهل الشرك

Verily, he is the slayer of every tribe of the polytheists.

ألا إنه المدرك بكل ثار لاولياء الله عزوجل

Verily, he is the one who will seek vengeance for all the friends of Allah, the Mighty and Majestic.

ألا أنه الناصر لدين الله

Verily, he is the helper of Allah's religion.

ألا إنه الغراف من بحر عميق

Verily, he is the one who draws from a deep ocean (of knowledge).

ألا إنه قسيم كل ذي فضل بفضله وكل ذي جهل بجهله

Verily, he is the one who shall mark out every person of merit by their merit, and every person of ignorance by their ignorance.

ألا إنه خيرة الله ومختاره

Verily, he is the best of Allah's creation and His chosen one.

ألا إن وارث كل علم والمحيط به

Verily, he is the inheritor of all knowledge and the one who encompasses it.

إلا إنه المخبر عن ربه عزوجل والمنبه بأمر إيمانه

Verily, he is the one who informs on behalf of his Lord, the Mighty and Majestic, and who raises awareness of the matter of His faith.

ألا إنه الرشيد السديد

Verily, he is the Rightly-guided, the one of sound judgment.

ألا إنه المفوض إليه

Verily, he is the one to whom all matters are entrusted.

ألا إنه قد بشر به من سلف بين يديه

Verily, he is the one who has been foretold by those who preceded him.

ألا إنه الباقي حجة ولا حجة بعده

Verily, he is the remaining Proof (of Allah), and there is no proof after him.

ولا حق إلا معه، ولا نور إلا عنده

There is no truth except with him, and no light except from him.

ألا إنه لا غالب له ولا منصور عليه

Verily, none can overcome him, and none can be aided to victory against him.

ألا وإنه ولي الله في أرضه وحكمه في خلقه وأمينه في سره وعلانيته

And verily, he is the Guardian of God upon His earth, His Judge among His creation, and His Trustee of His secrets and His manifest affairs.

[Source: al-Ehtejaj, Vol. 1, Pg. 80]