Does Bible impose any type of mandatory prayer that you have to offer at particular time or particular day? If so, what are some important prayers? Is a prayer at Church more worthy than a prayer at home?
The closest would be the model prayer given in Matthew chapter 6 as part of the Sermon on the Mount. This prayer is understood by most to be an example, or model, rather than something to be repeated verbatim.
So, no, there are no specific mandatory prayers given in scripture, other than that we are to pray — and to pray without ceasing. Mandatory prayers reflect an ethos that is more about rule keeping. While there are rules, Christianity is not really about rule keeping: it's about building a relationship with God, and by extension your fellow man.
Truly, there is no place in the Bible where you can find MANDATORY prayer. But Jesus gave us some guidelines on how we should pray and what the content of our prayer should be.
Recommended is the Lord's prayer which I found sufficient to cater for all needs of a christian. This doesn't mean you have to pray it verbatim but reflect on every part of it and pray it in your own words.
The Lord's prayer encourages approaching God in prayer like a child to Father, that every christian should anticipate the coming of christ and value doing the will of God. Daily provision of food, Deliverance from evil, grace not to fall into temptation, forgiveness of sins and so on.
Sticking to this alone is enough for a christian to be sustained in life journey and the christian journey.
To Catholics, observance of the Sabbath as mandated by the 3rd commandment:
is observed by the precept of the church
and, as a prayer
it ranks right up there. Even if one doesn't consider the Mass a prayer, it certainly contains lots and lots of prayers and lots and lots of scripture.
But, there is another prayer that all Christians must pray, because prayer is more than verbal. One must contemplate Jesus
And, in so doing, one must pray.
Finally there's the Lord's Prayer, which has been noted elsewhere, I wasn't going to mention it, but people are claiming that it was never meant to be repeated. Well...
To many protestants this:
May seem more familiar, or at least the end, and they sure as heck didn't get it from the Bible. I think they got it from the Didache Chapter 8, the apocryphal, but still pretty holy, book of the compiled wisdom of the Apostles, by way of the Catholic Church which preserved the tradition, but lost the manuscript.
So, owing to the age of this book (certainly older than Eusebius of Caesarea who wrote about it in the 4th century), it's pretty clear that the Lord's Prayer was interpreted as "the what to pray" if you want to be a Christian.