Discussion of the verse “So stand firm and straight (on the religion of Islamic Monotheism) as you are commanded”

Allah, may He be glorified and exalted, said to His Prophet
(blessings and peace of Allah be upon him):

“So stand firm and straight (on the religion of Islamic
Monotheism) as you are commanded, you and those (your companions) who turn
in repentance (unto Allah) with you, and transgress not (Allah’s legal
limits). Verily, He is All-Seer of what you do”

[Hood 11:112].

Ibn Jareer (may Allah have mercy on him) said: 

Here Allah, may He be exalted, says to His Prophet Muhammad
(blessings and peace of Allah be upon him): stand firm and straight as your
Lord has commanded, you and those who follow you in that, and call upon Him,
as your Lord has commanded, and those who return with you to obedience to
Allah and act in accordance with what their Lord has commanded, after they
had disbelieved; and do not transgress against His command and do that which
He has prohibited to you, for your Lord has knowledge of all the deeds that
you do – both deeds of obedience and disobedience – and nothing of that is
hidden from Him, for He sees all of it. So fear Allah, O people, lest your
Lord look upon you when you are doing something contrary to His command, for
He knows all that you do, and He is constantly watching you.

End quote from Tafseer at-Tabari (15/499) 

Ibn Katheer (may Allah have mercy on him) said: 

Here Allah, may He be exalted, instructs His Messenger and
His believing slaves to be steadfast and persist in righteousness, for that
is one of the greatest means of help towards victory over one’s enemies and
going against one’s opponents. And He forbids transgression, which is
wrongdoing, for that is a fatal error even if it is against a mushrik. And
remember that Allah, may He be exalted, sees all that people do, and He is
not unaware of anything, and nothing is hidden from Him.

End quote from Tafseer Ibn Katheer (4/354)

 This came after Allah, may He be glorified and exalted, had
mentioned the situation of those who are blessed and those who are doomed,
and after He, may He be exalted, had said, addressing His Prophet (blessings
and peace of Allah be upon him):

“So be not in
doubt (O Muhammad (blessings and peace of Allah be upon him)) as to what
these (pagans and polytheists) men worship. They worship nothing but what
their fathers worshipped before (them). And verily, We shall repay them in
full their portion without diminution.

Indeed, We gave the Book to Moosa (Moses), but differences
arose therein, and had it not been for a Word that had gone forth before
from your Lord, the case would have been judged between them, and indeed
they are in grave doubt concerning it (this Qur’an).

And verily, to each of them your Lord will repay their works
in full. Surely, He is All-Aware of what they do”

[Hood 11:109-111]. 

Having spoken of the situation of both parties, and mentioned
the disbelief of those who worshipped idols alongside Allah, and that those
who differed concerning the Book became divided into factions, Allah then
instructed His Prophet Muhammad (blessings and peace of Allah be upon him),
and the believers who were with him, to stand firm and straight (on the
religion of Islamic Monotheism) as they were commanded, and follow the laws
that Allah had prescribed, and to accept the sound beliefs of which Allah
had told them, and not to deviate from that to the right or to the left, and
to persist in that, and not to transgress by overstepping the limits of
righteousness that Allah had set for them.

End quote from Tafseer as-Sa‘di (p. 390) 

We did not find any particular story or incident because of
which this verse was revealed. But the context of these verses indicates
that the meaning of the verse has to do with what comes before it of the
description of those who are blessed and those who are doomed, and the state
of the mushrikeen and those who differed concerning the Book. So it is an
instruction to the Prophet (blessings and peace of Allah be upon him) and
those who believed with him, telling them to stand firm and straight, and
not to deviate or overstep the mark. Hence it begins with the word fa
(translated here as “so”), in the phrase
“So stand firm and straight”,
which connects it to what comes before it. 

To sum up the meaning: You – O noble Messenger – know the
situation of those who are blessed and the situation of those who are
doomed, and We have told you of the situation of the mushrikeen and the
situation of those who differed concerning the Book, and We have told you
that every accountable person will be requited in full for his deeds. So
adhere, you and the believers with you, to the path of adherence to the
truth, and persist in that as Allah has commanded you, without being
heedless or going to excess, and beware of overstepping the limits of
moderation in all your words and deeds; do not be like those who became
divided and differed after clear proof had come to them, so that you may be
among those who are blessed, and not be among those who are doomed. 

Therefore, when a man came to the Prophet (blessings and
peace of Allah be upon him) and said: O Messenger of Allah, tell me of
something in Islam that I shall not ask anyone else about after you. He
said: “Say, ‘I believe in Allah,’ then stand firm and straight.”

Narrated by Ahmad (14991) and at-Tirmidhi (2410); classed as
saheeh by al-Albaani in Saheeh at-Tirmidhi 

And Allah knows best.