I don't know of any command saying that one should pray every morning and every evening. There is a command to read the Writings at these times, though.
Yes this is in the notesof the Kitab-i-Aqdas
165. Recite ye the verses of God every morn and eventide. # 149
Bahá'u'lláh states that the essential "requisite" for reciting "the verses of God" is the "eagerness and love" of the believers to "read the Word of God" (Q and A 68).
With regard to the definition of "verses of God", Bahá'u'lláh states that it refers to "all that hath been sent down from the Heaven of Divine Utterance". Shoghi Effendi, in a letter written to one of the believers in the East, has clarified that the term "verses of God" does not include the writings of Abdu'l-Bahá; he has likewise indicated that this term does not apply to his own writings
Baha'u'llah : The Kitab-i-Aqdas - Notes
This is an important aspect to consider
"..Shoghi Effendi, in a letter written to one of the believers in the East, has clarified that the term "verses of God" does not include the writings of Abdu'l-Bahá; he has likewise indicated that this term does not apply to his own writings..."
Regards Tony