Of Prayer: Which is the third petition?

Heidelberg Catechism (extended)

The Catechism
Method of Instruction in the Christian Religion
As the Same is Taught in the Reformed Churches and Schools

(with the Scripture references written out)

Note. This Catechism is fully based on the Scriptures. The references to Scripture are indicated in parentheses with a letter. For example, the letter (a) points to the texts (a) placed after the answer.

Of Prayer

49. Lord's Day 

Q. 124. Which is the third petition? 

A. "Thy will be done on earth as it is in heaven"; that is, grant that we and all men may renounce our own will, (a) and without murmuring obey thy will, which is only good; (b) that every one may attend to, and perform the duties of his station and calling, (c) as willingly and faithfully as the angels do in heaven. (d) 

(a) Matt.16:24 Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me. Tit.2:11 For the grace of God that bringeth salvation hath appeared to all men, Tit.2:12 Teaching us that, denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world; 

(b) Luke 22:42 Saying, Father, if thou be willing, remove this cup from me: nevertheless not my will, but thine, be done. Eph.5:10 Proving what is acceptable unto the Lord. Rom.12:2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God. 

(c) 1 Cor.7:24 Brethren, let every man, wherein he is called, therein abide with God. 

(d) Ps.103:20 Bless the LORD, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word. Ps.103:21 Bless ye the LORD, all ye his hosts; ye ministers of his, that do his pleasure.

Source: http://www.ccel.org/creeds/heidelberg-cat-ext.txt