ESV - 23 But whoever has doubts is condemned if he eats, because the eating is not from faith. For whatever does not proceed from faith is sin.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
There is no scripture in the bible that intimates in any way, shape or form, that we should in any way, shape or form, limit our prayers.
The scripture listed here that mentions doubt and faith (Romans 14:23), isn't speaking to us about prayer. It has absolutely nothing to do with prayer. The whole 14th chapter of Romans is talking about the issue that some of the new believers had about certain foods, and days that were believed by some to be mandated as holy days. The verse mentions eating twice, it says nothing about praying.
The only place I know of where prayer is in any way questioned is in 1John 5:16 about "sin leading to death." He says 'I do not say that he should pray about that.' It should be noted that John didn't say to not pray about it.
1Thessalonians 5:17 - Pray without ceasing. Romans 1:9 - God is my witness... without ceasing I make mention of you always in my prayers... Colossians 1:9 - For this reason we also.... do not cease to pray for you... 1Samuel 12:23 - Far be it from me that I should sin against the LORD in ceasing to pray for you.... 2Timothy 1:3 - ...without ceasing I remember you in my prayers day and night.
There is never a reason to put prayer on the back burner. I wouldn't listen to anyone who told me differently.
I have heard too many times that the Lord's prayer should not be used as a repetitive prayer each day, but I have led my prayers to the Lord with that prayer as Luke 11:2 says when Jesus said, "When you pray, say this:" I pray for many other people and things that are troubling, or for gratitude in thanking God, even for a warm house and a dry roof, but it is troubling when pastors say that this is just a suggested model prayer not to be used repetitively. Yet every day carries many of the same things requested in that prayer.
The preceding verses tell us not to do as the gentiles do with repetition, but I have always thought that to mean the "chanting of meaningless repetition", and not the substance of the Lord's Prayer. One more thing, it seems that many people and pastors are so afraid of repetition, that I never hear the Lord's Prayer" at all during service. It is disturbing to me, and so sad.