Translation of the verse 1 from Surah sad : Number of verses 88 - - page 453 - Part 23.
Sad [These letters (Sad etc.) are one of the miracles of the Quran and none but Allah (Alone) knows their meanings]. By the Quran full of reminding.
Sad. By the Qur'an containing reminder...
(38:1) Sad, *1 and by the Qur'an full of exhortation! *2
*1) Although like alI other enigmatic letters (mugatta'at) it is difficult to determine the meaning of the letter Suad also, yet the interpretation of it given by Ibn 'Abbas and Dahhak is quite plausible. According to them, it implies: Sadiq-un fi' qauli-hi, or Sadaqa Muhammad-un: Muhammad (upon whom be Allah's peace and blessings) is Truthful: whatever he says is the very Truth.
*2) The words dhi-dh-dhikr of the Text can have two meanings: (1) Dhi sharaf: the noble Qur'an; and (2) Dhi at-tadhkir: the Qur'an which is full of admonition, or the Qur'an which serves as a reminder, or arouses a heedless person.
Source : sad Verse 1: Sad. By the Qur'an containing reminder...