How authentic is the Hadeeth in which the Prophet, sallallaahu ‘alayhi wa sallam, said that the best names are those which begin with the word "‘Abd" followed by one of The Names of Allaah; and those names which are derivatives of the word Hamd, such as Muhammad, Ahmad, etc.? Does the name Hamad have the same merit as Ahmad and Muhammad?

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

This is a widely circulated saying and its attribution to the Prophet, sallallaahu ‘alayhi wa sallam, is invalid and has no basis. Al-‘Ajlooni pointed out that there is no basis for the claimed virtue of having a name like Ahmad or Muhammad.

As for the last part of the question; if we presume that the Hadeeth is authentic, then it is apparent that the names Hamd or Hamad are included in this Hadeeth (had it been an authentic one).

Allaah Knows best.