The Holy Prophet Peace and Blessings of Allah be Upon Him has two personal names. He is known as Ahmad in the past scriptures and Muhammad in the Holy Qur'an. There are countless attributive names of Sayyiduna Rasoolullah Peace and Blessings of Allah be Upon Him. He is known by a distinct name in different areas. Every area (skies, earth, oceans, mountains, etc.) knows him by a special name and he is addressed accordingly.
There are numerous Fadha'il (Excellence and Benefits) of keeping the names "AHMAD" and "MUHAMMAD" as mentioned in many sayings (Ahadith) of the best of the Creation; the Master of Mankind Peace and Blessings of Allah be Upon Him. Few of them are given below:
1. It is stated in Tibrani that the Holy Prophet Sallallaho Alaihi wa Aalihi wa Sallam said, "Keep the names (of your children) on my name and not on my Kunniyat (Title)."
2. Ibn Asakir and Hussain Ibn Ahmad has stated that Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam said, "If a son is born to you and out of love and respect for me and to obtain the blessings of my name, you keep the child's name 'Muhammad', then the father and child will both enter Jannah."
3. Hafidh Abu Tahir and Hafidh Ibn Bakeer narrates on the authority of Sayyiduna Anas Radi Allahu Ta'ala Anhu that Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam said, "On the day of Qiyamah two persons will be summoned to the Court of ALLAH. The verdict would be - 'take them both to Jannah!' They would say, 'O Almighty ALLAH! We have performed no good deed to entitle us to enter Jannah!' ALLAH will command again, 'Take them to Jannah because I have taken an oath that I will not put any person in Jahannam (Hell) whose name is Ahmad or Muhammad.'"
NOTE: Elaborating on the above Hadith, A'laHadrat Imam Ahmad Rida (Radi ALLAHu Ta'ala Anhu) states: "That person is a Mu'min (Believer) and according to the Quran, the Hadith and the Sahaba, a Mu'min is he who has sound and correct beliefs of the Ahle Sunnah Wa Jama'ah, that is, 'Sunni Sahih-ul-Aqida'. On the contrary, as for those who are misled and possess incorrect Aqaid are, according to Hadith Shareef, dogs of Jahannam whose deeds are rejected, and even if they are innocently murdered between Hajre Aswad and Makame Ibraheem and have Sabr and hopes for reward from ALLAH, then too ALLAH will not show any mercy towards them but sentence them to Hell. These Ahadith have been narrated by Daarqutni, Ibn Majah, Baihaqi and Ibn Jawzi etc from Hadrat Abu Umaama and Hadrat Huzaifa and Hadrat Anas (Radi Allahu Ra'aala Anhum Ajma'een) and this faqeer (AlaHadrat) has quoted these narrations in numerous of his Fatawa. Now, it must be noted that there is no glad tidings in this Hadith (about those whose names are Muhammad and Ahmad), for kuffaar like Muhammed bin Abdul Wahab Najdi or Sayid Ahmed Khan whose maslak is clearly kufr, since even the fragrance of Jannat is definitely haraam upon the kaafirs." [Ahkaam-e-Shariat]
4. Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam states: "My Lord has mentioned to me, 'I swear by My Sight and greatness that whosoever is named after you shall never be destroyed by the Fire of Hell.'" [Hilyah Abu Nu'aym]
5. Ameer al-Mu'mineen Sayyiduna Ali (Radi ALLAHu Ta'ala Anhu) narrates that Rasoollulah Sallallaho Alaihi wa Aalihi wa Sallam states: "Those who sit in a company and eat food, and if there is a person amongst them by the name of Ahmad or Muhammad, then that entire group would receive the blessing of ALLAH twice daily." [Hafidh Ibne Bakeer, Waylami, Musnad Abi Saeed Naqqash, Ibn Adi Kaamil]
Shortly, in homes where persons with these sacred names live, ALLAH blesses that home twice daily.
6. Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam states: "What would you lose if in your homes there is one, two or three Muhammad's." [Tabaqat Ibne Sa'ad]
7. Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam states: "When a group sit in consultation and if a person by the name of Muhammad is amongst them, but is not included in such a meeting, ALLAH does not bestow Barakah in such a meeting." [Taraifi, Ibne Jawzi]
8. The Glorious Prophet of ALLAH Sallallaho Alaihi wa Aalihi wa Sallam said: "He who is blessed with three sons and does not name one Muhammad is indeed a Jahil (Ignorant)." [Tibrani, Mau'jam al-Kabeer]
9. The Holy Prophet Sallallaho Alaihi wa Aalihi wa Sallam said: "When you name the child Muhammad, respect him, make place and accommodate him in a gathering and do not accuse or curse him." [Hakim, Musnad al-Firdous, etc.]
10. Sayyiduna Rasoolullah Sallallaho Alaihi wa Aalihi wa Sallam said: "When you name your son Muhammad, do not hit him, deprive him or rob him." [Musnad, Bazar]
It is preferable (MustaHsan) to keep the child's name "Muhammad" alone and not to add any name to it because the excellence of the sacred name alone has been mentioned in the aHadith. [An Nooru Wad Diya, pages 18 to 24]
11. Imam Sakhaawi narrated on the authority of Imam Ataa (Radi Allahu Anhu) [Taabi’ee, who is the distinguished Teacher of Imam al-A’ima Sayyidina Imam al-Azam Abu Hanifa Radi Allahu Anhuma] as follows: “One who wishes for his pregnant wife to have a boy baby, he should place his hand on her stomach and say,
إن كان هذا الحمل ذكراً فقد سميته محمداً
If it is a boy, then I have named him Muhammad.
Insha Allah a boy will be born.”