You can find a YouTube playlist here with many of the songs suggested below.
God’s covenant is a theme from the Old Testament and I give you my heart (CCLI), Waiting here for you (CCLI) and All my hope on God is founded (CH 192 / MP 16) are good gathering songs on this theme while also picking up on the image of the heart from v33. Every promise (CCLI / Getty) and Jesus, lover of my soul (CH 490 / MP 372) are more explicit about the new covenant bringing about pardon for our sin and Great is thy faithfulness (CH 153 / MP 200) and Let his praise be on our lips (Satellite) are more general options.
There are two reasonable metrical options for today’s psalm, which is the thirteenth part of Psalm 119. O how I love your law (Grace) has a good text but it’s worth looking at another Short Meter tune such as Carlisle or Garelochside. My constant meditation here (PCE / CCLI) is written for Stracathro and interestingly is part of an attempt to write an acrostic version of the psalm in English, so every second line begins with ‘m’. I long for your commandments (Hymnary) is another option as it attempts to bring together themes from across the whole of the psalm.
The Gospel is the first of two parables Jesus’ tells about the need to pray and some classic hymns which could link to this include What a friend we have in Jesus (CH 547 / MP 746) as well as two songs by James Montgomery - Lord, teach us how to pray aright (CH 545) and Prayer is the soul’s sincere desire (CH 546). Blest be God (CH 267) from the Philippines and Lord you hear the cry (Lord have mercy) (Resound) with its gospel feel, would both link to persistence in prayer, particularly for those who are marginalised in society such as the widow. The famous Taizé chant O Lord, hear my prayer (GIA / Hymnary) and Come, bring your burdens to God / Woza nomthwalo wakho (WGRG) from South Africa are wonderful short songs which could also be used as sung responses for prayers.
Songs which explore the importance of scripture can make a good response for the Epistle, such as Spirit of God, unseen as the wind (CH 600 / MP 1351), Thanks to God whose word was spoken (CH 605), Listen to the word which God has spoken (CH 780) and Your word, O Lord (Resound). God in scripture and in signs (GIA) explores how we seek God’s voice in scripture even when there are things we find challenging.
Our God has made his covenant new (Jubilate) is a direct response to the Old Testament reading, exploring what it means for us both personally and corporately. Help us, O Lord, to learn (STF 501) and My heart is filled with thankfulness (MP 1209 / CCLI) both reference God’s laws being written on our hearts while The Father’s song (MP 1063 / CCLI) also does this in a more poetic way.
The Epistle calls us to proclaim the message and there are a range of hymns that could pick up on this including We have a gospel to proclaim (CH 363 / MP 728), You are called to tell the story (CH 680), Go to the world! Go into all the earth (CH 683) and I will sing the wondrous story (MP 315). Some worship songs which could link are Mission’s Flame (CCLI) and Send me (CCLI) while El mensaje que hoy proclamamos / Hear the message we now are proclaiming (H 46) from Colombia and Murassala (WGRG / H 82) from South Sudan would both send people out dancing.