One day while the Prophet was sitting in the company of some people, (The angel) Jibraeel came and asked, "What is faith?" Allah's Apostle replied, 'Faith is to believe in Allah, His angels, (the) meeting with Him, His Apostles, and to believe in Resurrection." Then he further asked, "What is Islam?" Allah's Apostle replied, "To worship Allah Alone and none else, to offer prayers perfectly to pay the compulsory charity (Zakat) and to observe fasts during the month of Ramadan." Then he further asked, "What is Ihsan (perfection)?" Allah's Apostle replied, "To worship Allah as if you see Him, and if you cannot achieve this state of devotion then you must consider that He is looking at you." Then he further asked, "When will the Hour be established?" Allah's Apostle replied, "The answerer has no better knowledge than the questioner. But I will inform you about its portents.
1. When a slave (lady) gives birth to her master.
2. When the shepherds of black camels start boasting and competing with others in the construction of higher buildings. And the Hour is one of five things which nobody knows except Allah.
The Prophet then recited: "Verily, with Allah (Alone) is the knowledge of the Hour--." (31. 34) Then that man (Gabriel) left and the Prophet asked his companions to call him back, but they could not see him. Then the Prophet said, "That was Gabriel who came to teach the people their religion." Abu 'Abdullah said: He (the Prophet) considered all that as a part of faith.
"There is none worthy of Worship but Allah Muhammed is Allah's Messenger."
Some Other cholars has divided into three categories.
عِلْمٌ في الخَلْقِ مَوْجودٌ، وَعِلْمٌ في الخَلْقِ مَفْقودٌ؛ فَإِنْكارُ العِلْمِ المَوْجودِ كُفْرٌ، وَادِّعاءُ العِلْمِ المَفْقودِ كُفْرٌ.
وَلا يَصِحُّ الإِيمانُ إِلاَّ بـِقَبولِ العِلْمِ المَوْجودِ، وَتَرْكِ طَلَبِ العِلْمِ المَفْقودِ.
Whatever is made by Allah is under Allah’s. He owns everything. He uses everything and Allah can change shapes of everything by his power and he can change their qualities without changing their shapes. He can change a stick into a snake and a snake into a stick. Similarly he controls everything whether land (kingdom) or wealth, electrical or gaseous. He uses these things as he likes. He can bring about destruction from the means of creations and he can show creation from the means of destruction.He runs the system of sustenance. If he wishes he can sustain somebody in a barren desert without any source of material and he can spoil life even in the midst of plenty of materials.
"I believe in what Allah revealed according to the meaning that Allah willed, and in what the Messenger of Allah conveyed according to the meaning that the Messenger of Allah willed."
Imam Tahawi R.A. has ended his Famous book Al-`Aqida Al-Tahawiyya with these word that also works as Advice for Muslims
وَنَحْنُ نَبْرَأُ إِلى اللَّهِ تَعالى مِمَّنْ خالَفَ الَّذي ذكَرْناهُ، وَبَيَّناهُ.
وَاللَّهُ أَعْلَمُ بالصَّوابِ، وَإِلَيْهِ المَرْجعُ وَالمَآبُ.