“See that you do not despise one of these little ones. For I tell you that their angels in heaven always see the face of my Father in heaven." - Matthew 18:10
Job 33:23-6 describes Angels as guide and intercessors for men:
23 Yet if there is an angel at their side,
a messenger, one out of a thousand,
sent to tell them how to be upright,
24 and he is gracious to that person and says to God,
‘Spare them from going down to the pit;
I have found a ransom for them—
25 let their flesh be renewed like a child’s;
let them be restored as in the days of their youth’—
26 then that person can pray to God and find favor with him,
they will see God’s face and shout for joy;
he will restore them to full well-being.
Daniel 6:22
My God sent his angel, and he shut the mouths of the lions. They have not hurt me, because I was found innocent in his sight. Nor have I ever done any wrong before you, Your Majesty.
and
Daniel 3:28
Then Nebuchadnezzar said, “Praise be to the God of Shadrach, Meshach and Abednego, who has sent his angel and rescued his servants! They trusted in him and defied the king’s command and were willing to give up their lives rather than serve or worship any god except their own God.
The early monastic traditions held great care in devotion to angels. Saint Benedict and Saint Bernard of Clairvaux both eloquently wrote descriptions and papers of the angels.
Brethren, we will love God's angels with a most affectionate love; for they will be our heavenly co-heirs some day, these spirits who now are sent by the Father to be our protectors and our guides. With such bodyguards, what are we to fear? They can neither be subdued nor deceived; nor is there any possibility at all that they should go astray who are to guard us in all our ways. They are trustworthy, they are intelligent, they are strong — why, then, do we tremble? We need only to follow them, remain close to them, and we will dwell in the protection of the Most High God. So as often as you sense the approach of any grave temptation or some crushing sorrow hangs over you, invoke your protector, your leader, your helper in every situation. Call out to him and say: Lord, save us, we are perishing. —St. Bernard
Other examples in the New Testament (apart from Matthew) of guardian angels include
Acts 12:12-15
12 When this had dawned on him, he went to the house of Mary the mother of John, also called Mark, where many people had gathered and were praying. 13 Peter knocked at the outer entrance, and a servant named Rhoda came to answer the door. 14 When she recognized Peter’s voice, she was so overjoyed she ran back without opening it and exclaimed, “Peter is at the door!”
15 “You’re out of your mind,” they told her. When she kept insisting that it was so, they said, “It must be his angel.”
And
Hebrews 1:14
"Are they not all ministering spirits, sent to minister for them, who shall receive the inheritance of salvation?"
Our early records of this Memorial and feast first appear in records kept by the Franciscan order in 1500. During this time, in Spain the feats originally was held on March 1st. After Spain, the country of France began to celebrate the memorial but on September 29th. In 1607, Pope Paul V placed the feast into the General Roman Calendar ranked a double intended to supplement the Feast of Saint Michael. Pope Clement the X elevated the feast to the rank of a double and Pope Leo XIII raised the feast to the rank of a double major. On October 2nd, 1795, Pope Pius VI granted a partial indulgence for making the Devotions to our Guardian Angels and Patron Saints and a plenary indulgence to those who make the devotion twice a day for the entire year.
The Devotion read:
"O Angel of God, to whose holy care I am committed by the supernal clemency, enlighten, protect, defend, and govern me. Amen."
The Angel of God prayer for intercession reads as:
Ángele Dei,
qui custos es mei,
me tibi commissum pietáte supérna,
hodie illúmina, custódi, rege et gubérna.
Amen.
Angel of God, My guardian Dear,
To whom God's love commits me here,
Ever this "day" (or "night" if you say it at bedtime),
Be at my Side,
To light and guard,
To rule and guide,
Amen
For more information on Guardian Angels, we recommend watching
https://www.youtube.com/watch?v=3jo9giGsQWY&t