Depending on who is counting, there are between 600 and 3000 plus direct quotes, references, allegories to Old Testament Scripture though I am uncertain if each and every book is mentioned.
There are books in the Old Testament, letters are in the New Testament.
If you mean in the book of Psalms, there are 150. In addition to these, there are others that are not included in the Old Testament, the so-called psalm 151, 152 plus a few others. These also stem from Hebrew roots of about that time, but never found their way into the Hebrew 'songbook' the psalms.
The New Testament refers to Jesus over 950 times.
The Old Testament (or Hebrew Bible) was written almost entirely in Hebrew. Some parts of the Old Testament were written in Aramaic. The New Testament was written in Greek.
The word "clean" is found many, many times in the Bible. Scriptural references (at least in the NIV version) that use the word "clean" can mostly be found in the book of Leviticus. Leviticus is the third book of the Old Testament.
The book of Hebrews in the New Testament is often described as a letter to the Jews, emphasizing the supremacy of Jesus Christ and his role in fulfilling the Old Testament covenant. It also contains references to many Old Testament saints who demonstrated great faith, earning them a place in the "hall of fame" of believers.
There are over 500 references to the Old Testament in the Book of Revelation, reflecting a deep connection between the two texts. These references serve to provide context, symbolism, and continuity within the biblical narrative.
twiceAnother Answer:There are over 30 references to Jesus using the term lamb - direct or indirect. The vast majority of these are in the Book of Revelation.
There are no books called "letters" (or epistles) in the Hebrew Old Testament. All books that are designated as "letters" are Greek, and found in the New Testament.
The Old Testament was originally written in Hebrew. The New Testament was originally written in Greek.
Yes, there were references to sickness in the Old Testament. For example, in the Book of Job, Job suffered from painful sores. Additionally, in the Book of Kings, there are accounts of various illnesses affecting individuals.