on the authority of aboo 'amr - and he is also called aboo 'amrah - sufyaan bin abdillaah ath-thaqafee (radiallaahu anhu) who said :

it was related by muslim.

explanation of hadeeth number 21

the meaning of his (radiallaahu anhu) statement "tell me something about al-islaam which i can ask of no one but you" is that he is asking the prophet (sallallaahu alayhi wa sallam) to teach him a comprehensive statement about the meaning of al-islaam, that is clear in and of itself, and does not require any further explanation by anyone other than the prophet (sallallaahu alayhi wa sallam), such that he may act upon it and protect himself (from the fire) with it. so the prophet (sallallaahu alayhi wa sallam) replied to his question with his statement : "say: i believe in allaah - and then be steadfast".

this is from the complete and comprehensive speech that has been given to our messenger (sallallaahu alayhi wa sallam), for verily he (sallallaahu alayhi wa sallam) has combined, for the questioner, in these two phrases the complete meanings of al-islaam and al-eemaan. for verily these words instruct one to renew one's eemaan through the tongue and the remembrance of the heart, and they instruct one to remain steadfast (have istiqaamah) upon performing the actions of obedience and to refrain completely from all the actions of disobedience, since it is not possible to establish al-istiqaamah while at the same time having some element of crookedness and disobedience, as this is its opposite. and this is similar to his statement : "verily, those who say: 'our lord is allaah', and then they remain steadfast upon that" [fussilat, 30], ie they believe in allaah alone, and then they remain steadfast upon that, and upon his obedience, until allaah takes their souls and they are still upon that. 'umar bin al-khattaab (radiallaahu anhu) said : "they are steadfast upon the obedience of allaah, and they do not swerve away from that with the evasions of the fox". and its meaning is that they are firm upon most of what allaah has ordered, from the matters of belief, speech and action. and they persist upon that, and this is the meaning of the explanation given by most of the scholars of tafseer, and it is the meaning of the hadeeth, in shaa' allaah ta'aalaa.

and similarly the statement of allaah subhaanahu : "so stand (o muhammad saw) firm and straight (on the religion of islaam) as you are commanded" [hood, 112]. ibn 'abbaas (radiallaahu anhu) said that no other verse from the entire qur'aan was revealed upon the messenger (sallallaahu alayhi wa sallam) that was harder upon him than this verse. and due to this he sallallaahu alayhi wa sallam said : "(the soorah) hood and its companions have made my hair white". and aboo bakr (radiallaahu anhu) has narrated that he (sallallaahu alayhi wa sallam) said : "my hair has been made white by (soorahs) hood, and al-waaqi'ah, and al-mursalaat, and 'amma yatasaa'aloon, and idha ash-shamsu kuwwirat".

al-ustaadh aboo al-qaasim al-qushairee (rahimahu allaahu ta'aalaa) said : al-istiqaamah is a station by which is achieved the perfection of the affairs, and their completion, and with its presence one attains all that is good and in order. and he who does not attain istiqaamah in his endeavour then he has lost that endeavour and all good fortune.

and it is said : al-istiqaamah is not sustained except by the elders and seniors [in the deen], because it involves keeping away from the common [incorrect] practises of the [ignorant] people. and it involves difference and separation from the [incorrect] customs and traditions of the people, and instead standing firm between the hands of allaah ta'aalaa upon the reality of truth, and due to this the prophet (sallallaahu alayhi wa sallam) said "be steadfast [in your actions] and do not count/enumerate [your good actions, which may cause you to limit them]. and know that the best of your actions is the prayer, and none except the [true] believer takes care to maintain his wudoo'". and al-waasitee (rahimahu allaah) said : "al-istiqaamah is a trait such that with it all the good qualities are perfected, and without it they are all disfigured."

and allaah knows best.

summary :

• that only the messenger of allaah (sallallaahu alayhi wa sallam) fully understood the essence and worth of worshipping allaah truly
• that one must truly believe that allaah is his lord whom he worships, and then stay upright and steadfast upon that belief, and that covers the whole religion
• that keeping upright / steadfast is following the injunctions that have come from allaah in whom he trusts and whom he worships and whom he takes as the highest authority