Thank you for the question on the posture of prayer, “Where is there any place in the holy scripture it was written before we pray that we must close our eyes?”
Prayer is more of the posture of the heart than of the body.
Jesus says this in Luke 18, “9 To some who were confident of their own righteousness and looked down on everyone else, Jesus told this parable: 10 “Two men went up to the temple to pray, one a Pharisee and the other a tax collector. 11 The Pharisee stood by himself and prayed: ‘God, I thank you that I am not like other people—robbers, evildoers, adulterers—or even like this tax collector. 12 I fast twice a week and give a tenth of all I get.’ 13 “But the tax collector stood at a distance. He would not even look up to heaven, but beat his breast and said, ‘God, have mercy on me, a sinner.’ 14 “I tell you that this man, rather than the other, went home justified before God. For all those who exalt themselves will be humbled, and those who humble themselves will be exalted” (NIV).
The Pharisee looked up toward heaven, while the tax collector didn’t look even up to heaven. Bowing down before God reflects humility and closing one’s eyes may help a person become more focus on God alone. Praying with one’s eye open may cause a person to be distracted by what is seen. It may cause the person to be judgmental toward others who may be texting, whispering, shuffling around. It may even cause one to see how many nods one receives when one prays aloud.
When we think of the scene when Jesus being in the Garden of Gethsemane as he fell to the ground, what was his posture including his eyes as he spoke to God? Do you think it was opened or was it closed? It doesn’t really matter at all. The words which he uttered was from his heart and his kneeling or prostrating on the ground shows his submission to the Heavenly Father.
Personally, I close my eyes for when I see things it causes me to be distracted in my prayer.
Summary: God looks at the heart of the person, while man looks at the physical posture of oneself or others. If we do, we are not praying but judging.
-Kingston