And faith consists of both words and actions, and it increases and decreases. As Allah the Exalted has said: "That they may increase in faith along with their (present) faith." [سورة الفتح: 4] And He said: "And We increased them in guidance." [سورة الكهف: 13] And He said: "Allah increases in guidance those who are guided." [سورة مريم: 76] And He said: "Those who are guided, Allah increases them in guidance and grants them piety." [سورة محمد: 17] And He said: "The faith of those who believe increased." [سورة المدثر: 31] And He said: "Which of you has this surah increased in faith? Indeed, those who have believed, their faith has increased." [سورة التوبه: 124] And He said: "The hypocrites said to the believers: 'Indeed, the people have gathered against you, so fear them.' But it only increased them in faith, and they said: «حسبنا الله و نعم الوكيل» ." [سورة آل عمران: 173] And He said: "It increased them in nothing except faith and submission." [سورة الاحزاب: 22] And in the hadith it is mentioned that loving for the sake of Allah and hating for the sake of Allah is part of faith (narrated by Abu Dawud from Abu Umamah). And the caliph Umar ibn Abd al-Aziz, may Allah have mercy on him, wrote to Adi ibn Adi that faith consists of many obligations, beliefs, limits, and recommended and sunnah matters, all of which are included in faith. So whoever fulfills all of them has perfected his faith, and whoever observes them but does not fulfill them has not perfected his faith. So if I remain alive, I will explain all of them to you in detail so that you may act upon them, and if I die, then I have no desire to remain in your company.

And the saying of Ibrahim (peace be upon him) has been mentioned in the Noble Qur’an:“But I wish that my heart may be satisfied.”And Mu’adh (may Allah be pleased with him) once said to a companion (named Aswad bin Bilal):“Sit with us so that for a while we may discuss matters of faith.”And Abdullah bin Mas’ud (may Allah be pleased with him) said:“Certainty is complete faith”(and patience is half of faith. Narrated by al-Tabarani). And the saying of Abdullah bin Umar (may Allah be pleased with them both) is:“A servant does not reach the true reality of piety until he leaves what causes doubt in his heart.”And Mujahid (may Allah have mercy on him), in the explanation of the noble verse «شرع لکم من الدين» etc., said:“(He has ordained for you the same religion which He ordained for Nuh) means: O Muhammad! We have enjoined upon you and Nuh the same religion.”And Abdullah bin Abbas (may Allah be pleased with them both), regarding the noble verse «شرعة ومنهاجا‏» , said:“By this is meant «سبيل» (the straight path) and the Sunnah (the good way).”