I have been ordered to fight the people until they testify that none has the right to be worshipped (in truth) but Allāh and that Muḥammad is the Messenger of Allāh, and (until) they establish the prayer and give the zakāh. So if they do that, their blood and wealth is safeguarded from me, unless it pertains to a right of Islām, and their reckoning is with Allāh.

The Messenger of Allāh (ṣallallāhu alayhi wasallam) said, "Whoever introduces something into this affair of ours that is not from it will have it rejected."

Innovation( Bid'ah) in Religion is rejected

Level 1 - Islam"Islām is to bear witness that none has the right to be worshipped but Allāh and Muḥammad is the Messenger of Allāh, to establish the prayer, to pay the zakāh, to fast in Ramaḍān and to make pilgrimage to the House if you are able to do so. Level 2 - ImanĪmān is to believe in Allāh, His Angels, His Books, His Messengers, the Last Day, and to believe in the Divine Decree (and foreknowledge) Level 3 - IhsanIt is to worship Allāh as if you can see Him, and even though you cannot see Him, He most certainly sees you."

The 3 Levels in Islam

Islām is built upon five (pillars):<ol><li>The testimony that none has the right to be worshipped (in truth) but Allāh and that Muḥammad is the Messenger of Allāh</li><li>Establishing the (daily) prayer(s)</li><li>Giving the zakāh</li><li>Fasting in Ramaḍān</li><li>Pilgrimage to the house of Allah (Ka'ba, Makkah)</li></ol>

The five pillars of Islam

<ul><li>The first Stage in mother's womb over forty days as a nuṭfah</li><li>Then he is an ʿalaqah for a like period.</li><li>Then he is a muḍghah for a like period.</li><li>Then an angel is sent to it and it breathes the spirit into it</li><li>It is then commanded with four words:</li></ul><ol><li class="ql-indent-2"> -- the writing of its sustenance, </li><li class="ql-indent-1">-- its lifespan</li><li class="ql-indent-1">-- its deeds</li><li class="ql-indent-1">---whether happy or wretched (in the Hereafter). </li></ol>

The Stages of Creation of Mankind

That which is lawful is clear and that which is unlawful is clear and between the two are ambiguous matters which many people do not know of.So whoever took caution regarding the ambiguous matters has absolved himself regarding his religion and his honor. And whoever fell into the doubtful matters has fallen into the unlawful, just like the shepherd who grazes his flock around the sanctuary (of a king), all but grazing therein.Indeed, every king has a sanctuary (that cannot be violated) and indeed the sanctuary of Allāh is his prohibitions.

Doubtful Matters vs Clear Matters

"Verily actions are based upon the intentions (behind them) and every man shall have (in accordance) with what he intended. Thus, he whose migration was (for the sake of) Allāh and His Messenger, then his migration was indeed for Allāh and His Messenger. And he whose migration was to attain a portion of the world or to take some woman in marriage, then his migration was for that for which he migrated."

Actions Are By Intention

Indeed, there is a morsel of flesh in the body which if it is sound the whole body is sound and which if it is corrupt the whole body is corrupt. Indeed, it is the heart

That which corrupts the whole body

The Prophet (ṣallallāhu ʿalayhi wasallam) saidThe religion is sincerity of purpose.We said, "To whom?"He said,"To Allāh, His Book, His Messenger, the leaders of the Muslims and their general folk"

Islam = Sincerity of purpose

Imam Nawawi's (May Allah have mercy upon him) Forty is a compilation of forty hadiths by Imam al-Nawawi, most of which are from Sahih Muslim and Sahih al-Bukhari.