Grace Before Meals
First, the person praying should have a clean heart for the Lord to answer a prayer. If not for this way and condition, he will likely to receive a curse instead of blessings. And whoever will eat the cursed food can do so at their own destruction. Let us not assume that the food with a prayer done by someone else before meals is already clean.
Prov 15:8 The sacrifice of the wicked is an abomination to the LORD: but the prayer of the upright is his delight.
If you know that you are doing the will of god, why not pray for yourself? The prayer of a righteous person availeth much but God does not hear the prayer of the wicked.
Is 59:2 But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear.
Second, A Prayer is a direct communication between you and God so use it wisely. A Voluntary humility not according to the doctrine of Christ is not a sure way to salvation. Only God knows your heart not even satan.
Jer 17:9 The heart is deceitful above all things, and desperately wicked: who can know it?
Prov 16:25 There is a way that seemeth right to a man, but the end of it is the ways of death.
Prov 16:25 Col 2:18 Let no man beguile you of your reward in a voluntary humility and worshiping of angels, intruding into those things which he hath not seen, vainly puffed up by his fleshly mind,
Third, Anywhere and in any way, the prayer must be done in secret that no one can see. Pray in your mind that even the nearest person will never know what you are doing.
Mt 6:5 And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues, and in the corners of the streets, that they may be seen by men. Verily, I say to you, they have their reward.
Mat 6:6 But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father who is in secret, and thy Father who seeth in secret, will reward thee openly.
1 Cor 14:15 What should I do? I will pray with my spirit, but I will also pray with my mind. I will sing praises with my spirit, but I will also sing praises with my mind.
The hypocrites do pray where anyone could see. You can never pray in secret at public places doing the sign of the cross, closing your eyes, holding hands together or sprinkling of water. Any action or gesture that displays an act of prayer publicly is unscriptural and against the will of God.
The desire of your heart is hidden to Satan. Pray in secret to mislead him of his evil ways. If he knows your plan, he will work not to make your wishes to happen. Always remember, no one knows the heart except God.