Is Faith Just Verbal?
Question

We, Ahl as-Sunnah wal-Jama`ah, say that faith is verbal affirmation, belief in the heart and physical actions. What is the evidence for this view from the Quran and Sunnah?
Praise be to Allah.Faith is words, deeds and beliefs
Ahl As-Sunnah unanimously agreed that faith  is words and deeds, or verbal affirmation, belief in the heart and physical actions.
Ash-Shafi`i (may Allah have mercy on him) said: The consensus of the Companions and Tabi`in (the generation who came after the companions), those who came after them and those whom we met, was: Faith is words, deeds and intentions, and one of the three is not sufficient without the others.” (Usul I‘tiqad Ahl As-Sunnah by Al-Lalka’i (5/956, no. 1593); Majmu‘ Al-Fatawa by Ibn Taymiyah, 7/209)
Al-Bukhari (may Allah have mercy on him) said: “I narrated from a thousand of the scholars and more, but I only narrated from those who said that faith is words and deeds. I did not narrate from those who said that faith is words [only]." (Usul I‘tiqad Ahl As-Sunnah by Al-Lalka’i  5/959, no. 1597)
Abu `Ubayd Al-Qasim ibn Saaam (may Allah have mercy on him) said: “These are the names of those who said that faith is words and deeds, and it may increase and decrease . He named one hundred and thirty-three scholars, then he said: All of them say that faith is words and deeds, it may increase and decrease. This is the view of Ahl As-Sunnah and it is also our view. And Allah is the source of strength. (Quoted by Ibn Battah in Al-Ibanah (2/814, no. 1117); Shaykh Al-Islam in Majmu‘ Al-Fatawa, 7/309)
Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said: 
“More than one narrated that Ahl As-Sunnah wa'l-Hadith unanimously agreed that faith is words and deeds." (Majmu‘ Al-Fatawa, 7/330)
Evidence for the view that faith is words and deeds
The basis for this scholarly consensus is many texts of the Quran and Sunnah which indicate that words and deeds are part of faith. This may be explained in the following four points:

Words uttered by the tongue. This refers to all verbal acts of worship, which are part of faith. With regard to uttering the word of Islam, “La ilaha illa Allah, Muhammad Rasulullah (There is none worthy of worship except Allah, Muhammad is the Messenger of Allah), this is one of the pillars or essential parts of faith, which is not valid without it.

The evidence that words uttered by the tongue are part of faith includes the verse in which Allah, may He be Exalted, says (interpretation of the meaning):
{Say, [O believers], “We have believed in Allah and what has been revealed to us and what has been revealed to Abraham and Ishmael and Isaac and Jacob and the Descendants and what was given to Moses and Jesus and what was given to the prophets from their Lord. We make no distinction between any of them, and we are Muslims [in submission] to Him”.} [Al-Baqarah 2:136]
And the Prophet (blessings and peace of Allah be upon him) said: “I have been commanded to fight the people until they say La ilaha illa Allah. Whoever says La ilaha illa Allah, his life and his wealth are protected from me except in cases dictated by Islamic law, and his reckoning will be with Allah.” (Narrated by Al-Bukhari (2946) and Muslim (21) from Abu Hurayrah)
Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Faith has seventy-odd – or sixty-odd – branches, the best of which is saying La ilaha illa Allah, and the least of which is removing something harmful from the road, and modesty is a branch of faith.”  (Narrated by Al-Bukhari, 9 and Muslim, 35)

Belief in the heart , which is affirmation and certainty. The evidence that belief in the heart is part of faith is the verses in which Allah, may He be exalted, says (interpretation of the meaning):

{Those - He has decreed within their hearts faith.} [Al-Mujadilah 58:22]
{The believers are only the ones who have believed in Allah and His Messenger and then doubt not but strive with their properties and their lives in the cause of Allah . It is those who are the truthful.} [Al-Hujurat 49:15]
And the Prophet (blessings and peace of Allah be upon him) said regarding faith: “It is to believe in Allah, His angels, His Books, His Messengers, the Last Day, and to believe in al-qadar (the divine will and decree), both good and bad.” (Narrated by Muslim (8) from ‘Umar; it was also narrated by Al-Bukhari (50) from Abu Hurayrah)
And in the Hadith on intercession he said: “…I will say: ‘O Lord, my ummah, my ummah.’ It will be said to me: ‘Go, and whoever has in his heart faith that is smaller, smaller, smaller than a grain of mustard-seed, bring him out of the Fire.’ And I will go and do that.” (Narrated by Al-Bukhari, 7510 and Muslim, 193 from Anas (may Allah be pleased with him))

Deeds of the heart, which are sincerity, submission, fear, hope and love.

The evidence that these are part of faith is the passage in which Allah, may He be Exalted, says (interpretation of the meaning):
{The believers are only those who, when Allah is mentioned, their hearts become fearful, and when His verses are recited to them, it increases them in faith; and upon their Lord they rely,
The ones who establish prayer, and from what We have provided them, they spend
Those are the believers, truly. For them are degrees [of high position] with their Lord and forgiveness and noble provision.} [Al-Anfal 8:2-4] Modesty is a deed of the heart. 
The Prophet (blessings and peace of Allah be upon him) said: “Faith has seventy-odd – or sixty-odd – branches, the best of which is saying La ilaha illa Allah, and the least of which is removing something harmful from the road, and modesty is a branch of faith.”  (Narrated by Al-Bukhari, 9 and Muslim, 35)
Modesty (haya’) is a deed of the heart. The Hadith also indicates that words uttered on the tongue and physical actions are also part of faith  , as noted above.
It was narrated from Anas ibn Malik (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said: “There are three characteristics, whoever attains them has found the sweetness of faith: when Allah and His Messenger are dearer to him than all else, when he loves a man and does not love him except for the sake of Allah, and when he would hate to return to disbelief as he would hate to be thrown into the fire.” (Narrated by Al-Bukhari, 16 and Muslim, 43)
It is well known that love and hate are deeds of the heart, and this Hadith regards them as part of faith and, in fact, as factors by means of which a person may taste the sweetness of faith.

Physical actions, such as purification, prayer, fasting, Hajj, Jihad and so on.

The evidence that physical actions are part of faith include the verses in which Allah, may He be Exalted, says (interpretation of the meaning):
{And they were not commanded except to worship Allah, [being] sincere to Him in religion, inclining to truth, and to establish prayer and to give zakah. And that is the correct religion.} [Al-Bayyinah 98:5]
{The believers are only the ones who have believed in Allah and His Messenger and then doubt not but strive with their properties and their lives in the cause of Allah. It is those who are the truthful.} [Al-Hujurat 49:15]. Striving (Jihad) is a physical action. 
Similarly, Allah, may He be exalted, says (interpretation of the meaning):
{The believers are only those who, when Allah is mentioned, their hearts become fearful, and when His verses are recited to them, it increases them in faith; and upon their Lord they rely,
The ones who establish prayer, and from what We have provided them, they spend
Those are the believers, truly. For them are degrees [of high position] with their Lord and forgiveness and noble provision.} [Al-Anfal 8:2-4]
Establishing prayer and giving Zakah are physical actions, and here they are regarded as part of faith. Allah, may He be exalted, says (interpretation of the meaning):
{And never would Allah have caused you to lose your faith.} [Al-Baqarah 2:143]
What is referred to here is the prayers that they offered facing towards Jerusalem [the verse refers to the change of the Qiblah].
Al-Bukhari (may Allah have mercy on him) (1/16) included this verse in a chapter entitled: Prayer is part of faith.
The Prophet (blessings and peace of Allah be upon him) said to the delegation from the tribe of ‘Abd Al-Qays: “I instruct you to believe in Allah; do you know what believing in Allah means? It means testifying that there is none worthy of worship except Allah, establishing prayer, giving Zakah and giving one fifth of the war booty.” (Narrated by Al-Bukhari, 7556 and Muslim, 17 from Ibn ‘Abbas (may Allah be pleased with him))
There is a great deal of evidence for that, and the scholarly consensus regarding it is well known.
And Allah knows best.