The Time for the Adhkaar of Morning and Evening

The adhkar of evening start
after the sun passes the zenith (at the beginning of the time for Zuhr/afternoon
prayer) until the sun sets, and at the beginning of the night. The adhkar of
the morning start from the break of dawn until the sun passes the zenith.
Allah says (interpretation of the meaning): 

“… and glorify the praises of
your Lord before the rising of the sun, and before its setting.”

[Ta-Ha 20:130] 

“And remember your Lord within
yourself, humbly and with fear and without loudness in words in the mornings
and in the afternoons.”

[al-A’raf 7:205] 

“afternoon” means between ‘Asr
and Maghrib. 

And Allah says (interpretation
of the meaning): 

“So glorify Allah [above all
that (evil) they associate with Him (O believers)], when you come up to the
evening [i.e. offer the (Maghrib) sunset and (‘Isha) night prayers], and
when you enter the morning [i.e. offer the (Fajr) morning prayer].

And His are all the praises and
thanks in the heavens and the earth; and (glorify Him) in the afternoon
(i.e. offer ‘Asr prayer) and when you come up to the time, when the day
begins to decline (i.e. offer Zuhr prayer).”

[al-Room 30:17, 18] 

And Allah is the Source of
strength, may Allah send peace and blessings upon our Prophet Muhammad and
his family and  Companions. End quote. 

Standing Committee for Academic
Research and Issuing Fatwas 

Fatawa al-Lajnah al-Daimah
li’l-Buhooth al-‘Ilmiyyah wa’l-Ifta
(24/178) 

See also question no.

22765.

And
Allah knows best.