Sensing the need of the poor person and treating him kindly come under the heading of piety, for the attaining of which fasting was prescribed

Allah does not prescribe anything but for a wise reason,
whether people are aware of it or it is hidden from them, or they know part
of it and part of it is hidden from them. Allah has great wisdom that human
minds cannot comprehend. 

Allah, may He be exalted, has mentioned the wisdom behind the
prescription and obligation of fasting in the verse in which He says
(interpretation of the meaning):

“O you who
believe! Observing As-Saum (the fasting) is prescribed for you as it was
prescribed for those before you, that you may become Al-Muttaqoon (the
pious)”

[al-Baqarah 2:183]. 

Some of the scholars have stated that one of the issues of
piety that fasting encourages is so that the rich person will come to
understand the situation of the poor person, and how he suffers from hunger
and need, so that this will motivate him to treat him kindly and meet his
brother’s needs. This is part of piety. 

Taqwa (translated here as piety) is a general term which
includes doing all that is good and refraining from all that is evil. Ibn
Katheer (may Allah have mercy on him) said: 

Taqwa (piety) is a general term which includes doing all acts
of obedience and refraining from all evils. 

End quote from Tafseer Ibn Katheer (1/492) 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

Taqwa (piety) is a general term which includes doing all that
Allah has enjoined and refraining from all that He has forbidden, because
the word is derived from wiqaayah (protection); what it means is taking
measures to protect oneself from the punishment of Allah, and there is no
way to protect oneself from the punishment of Allah except by doing that
which He has enjoined and refraining from that which He has prohibited. 

End quote from Majmoo‘ Fataawa wa Rasaa’il al-‘Uthaymeen
(24/40). 

There is no text in the Holy Quran or in the Prophetic Sunnah
that specifically indicates that Allah, may He be exalted, has enjoined
fasting on us so that we may feel empathy with the poor. But those scholars
who mentioned that based it on the idea that this is included in the general
meaning of piety, which the Holy Qur’an states is the wisdom behind fasting,
and suggested that this is appropriate in the case of one who is fasting,
because it is known that Islamic teaching encourages helping others and
creating mutual love and compassion among the believers. 

As-Sa‘di (may Allah have mercy on him) said: 

Allah, may He be exalted, tells us of the wisdom behind the
prescription of fasting, as He says “that you may become Al-Muttaqoon
(the pious)”. Fasting is one of the greatest means of developing piety,
because it involves obeying the command of Allah and avoiding that which He
has forbidden. 

Part of the piety that fasting involves is that the fasting
person refrains from that which Allah has forbidden to him of food, drink,
intercourse and so on, to which he is naturally inclined, seeking thereby to
draw closer to Allah, hoping for His reward by giving up these things. This
is part of piety. Piety also includes the following:

The fasting person trains himself to remember that Allah, may
He be exalted, is always watching, so he gives up things that he desires
even though they may be available to him, because he knows that Allah is
watching him.

Fasting narrows the pathways of the Shayt@ân, who flows
through the son of Adam like blood. Fasting weakens the Shayt@ân’s influence
and reduces sins.

The fasting person usually does many acts of worship and
obedience, which are characteristics of piety.

By fasting, the rich man feels the pain of hunger, which
makes him inclined to help the poor and destitute. This is also a
characteristic of piety.

End quote from Tafseer as-Sa‘di (p. 86) 

Shaykh Muhammad al-Mukhtaar ash-Shinqeeti (may Allah preserve
him) said: 

In fasting there is much good, because it reminds the rich of
the poor and needy. If a person feels hunger and thirst, even though he
knows that at the end of the day he will be able to find food and drink, he
will remember the poor who do not find any food or drink, hence they said
that in this fast there is a great deal of good for the individual, as it
reminds him of the weak, especially if he is one of the rich and wealthy. 

The rich man may forget his brethren among the weak and poor
because of the wealth that he has, as Allah, may He be exalted, says
(interpretation of the meaning):

“Nay! Verily,
man does transgress all bounds (in disbelief and evil deed, etc.).

Because he considers himself self-sufficient”

[al-‘Alaq 96:6-7]. 

If a person feels himself to be self-sufficient, he will
become arrogant, but if he feels hunger as the poor feel hunger, and he
feels thirst as the poor feel thirst, that will motivate him to remember
these weak ones and show compassion towards them. End quote. 

Sharh Zaad al-Mustaqni‘
(7/100) 

Therefore we fast as an act of worship to Allah, may He be
exalted, and in obedience to Allah and His Messenger (blessings and peace of
Allah be upon him), so that we may attain piety and fear of Allah in our
hearts, which leads to happiness in both realms (this world and the
hereafter). And part of piety is feeling empathy for the poor, which will
motivate us to help them. 

See also question no. 26862 

And Allah knows best.