Assalaamu alaykum. A friend of mine said that you must give you third child Mohammed or else you are a miser, and he attributed this information to the Prophet, sallallaahu ‘alayhi wa sallam. Is this true?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.

There is no doubt that it is good and virtuous to name one's child Muhammad because it is the name of the master of the children of Adam. Jaabir, may Allah be pleased with him, narrated that the Prophet, sallallahu ‘alayhi wa sallam, said, "Name yourselves with my name, but do not bear my nickname (i.e. Abu Al-Qaasim)." [Al-Bukhaari and Muslim]

Moreover, the Prophet, sallallahu ‘alayhi wa sallam, said, "On the Day of Resurrection, you will be called by your names and your fathers' names; so give yourselves good names." [Abu Daawood, Ad-Daarimi, Ibn Hibbaan, and Ahmad]

Therefore, it is recommended to give his name and other good names, such as the names of the Prophets, to children. However, not giving children these names does not necessarily mean that a person is a miser or that it is disliked to give other names.

What was narrated from the Prophet, sallallahu ‘alayhi wa sallam, is that the miser is whoever hears his name and does not send peace and blessings upon him. He, sallallahu ‘alayhi wa sallam, said, "The miser is the one before whom I am mentioned and who does not invoke the blessings of Allah upon me." [Ahmad - At-Tirmithi classified this hadeeth as hasan saheeh (good or sound) and As-Suyooti graded it saheeh (sound)]

Scholars stated that the hadeeth means that one of the due rights of the Prophet, sallallahu ‘alayhi wa sallam, over us is to invoke the blessings and peace of Allah upon him if he is mentioned. Some scholars said that the one who does not invoke the blessings of Allah upon the Prophet, sallallahu ‘alayhi wa sallam, when he is mentioned is thus miserly with his own  self by depriving it of a great reward.

Allah knows best.