The idea of night and day prayer can be found in numerous Biblical contexts. The clearest Old Testament reference is found in Isaiah 62:6, 7 where God speaks through the Prophet saying, "On your walls, O Jerusalem, I have appointed watchmen; all day and all night they will never keep silent. You who remind the LORD, take no rest for yourselves; and give Him no rest until He establishes and makes Jerusalem a praise in the earth."
Jesus teaches on the value of night and day prayer in a parable recorded in Luke 18: (1) "Now He was telling them a parable to show that at all times they ought to pray and not to lose heart...(6) And the Lord said...(7) 'now, will not God bring about justice for His elect who cry to Him day and night, and will He delay long over them? (8) I tell you that He will bring about justice for them quickly..."

The Tabernacle of David is an excellent Biblical example of a "night and day" house of prayer. The Ark of the Covenant had been lost in battle to the Philistines. Shortly thereafter, though the Philistines returned the Ark to Israel, it was neglected by King Saul and left in relative obscurity for years. After David ascended to the throne, he immediately set out to bring the Ark of the Covenant (which represented the very Presence of God) back to a rightful place of prominence. In 1 Chronicles 16 we read:
And they brought in the Ark of God and placed it inside the tent which David had pitched for it...(4) he appointed some of the Levites as ministers before the ark of the LORD, even to celebrate and to thank and praise the LORD God of Israel...(37) So he left Asaph and his relatives there before the ark of the covenant of the LORD to minister before the ark continually, as every day's work required..."
In addition, we discover that David, in preparation for the ministry of the more permanent Temple of Solomon, revised the duties of the Levites to introduce continual musical worship before the Lord through 4,000 instrumentalists (1 Chronicles 23:5) and through 288 skillful singers divided into 24 divisions (1 Chronicles 25:7ff).

The term Harp and Bowl is taken from the description of heavenly worship found in Revelation 5:8: "...the twenty-four elders fell down before the Lamb, each one holding a harp and golden bowls full of incense, which are the prayers of the saints."
This heavenly pattern of worship reveals the power of musical praise combined and intermingled with intercessory prayer.

Here are several among many examples:

• Bangor, Ireland - in 555 A.D., a Celtic monk
  named Comgall and his co-worker Columbanus gathered 3,000 monks to a place called Bangor (the High Choir). They began a prayer meeting that continued with singing 24 hours a day for 300 years, resulting in the first Celtic missions movement in history.
• Clairvaux, France - in 1120 A.D., a Catholic monk named Bernard gathered 700 monks to a valley called Clairvaux (Valley of Light). They began a prayer meeting that continue d 24 hours a day for many years, resulting in a dynamic release of evangelism through signs and wonders across all of Europe.
• Herrnhut, Germany - in 1727 a German nobleman named Nicholaus Ludwig Count von Zinzendorf (1700-1760) gathered persecuted Christians to his large estate in Germany that he named Herrnhut (the Watch of the Lord). They began a prayer meeting that continued 24 hours a day for 120 years, resulting in the Moravian movement, the first Protestant missions movement in history. Herrnhut represents the reality that night and day prayer releases evangelism unto the Great Commission.
• Kansas City, MO - in May, 1999, Mike Bickle formed the International House of Prayer (IHOP) with a band of intercessors praying 18 hours a day. Since September, 1999 the IHOP-KC Intercessory Missions Base has been praying non-stop for 24 hours a day 7 days a week (approaching 10 years in 2009). IHOP-KC is well known for its teachings on the "bridal paradigm" of prayer (that prayer and worship arises most effectively out of the intimate relationship individual believers and the corporate Church has with God as the Bride of Christ) and for the "Harp and Bowl" prayer model which blends contemporary worship songs with sung and spoken Biblical prayers and spontaneous singing. (See www.ihop.org).