Although it is not uncommon to see Arabic lettering tattoos in the United States, many Muslims residing in Middle East countries like Iraq, Iran and Saudi Arabia (particularly followers of Islam) are staunchly against it. Informed readers may be scratching their heads and wondering, "But what about henna?" You are absolutely right.
Henna, the art of decorating the hands and feet with a paste made from the Hina plant, originated in the Middle East. The women there adorn their bodies with Henna to celebrate births, victories, birthdays, circumcisions and especially weddings. And yet tattoos are strictly forbidden because, unlike Henna, which washes off within several days, tattoos are permanent.
It is unlawful to have anything on your body which God did not create--tattoos, piercing, even plastic surgery procedures are an abomination. Unless it is done to eliminate pain, all surgeries which alter one's appearance in any way are against Islamic law.
Of course, this does not prevent Arabs and non-Arabs alike from getting Arabic tattoos. I always recommend consulting several different sources if you're looking to translate an English word or phrase into a foreign language and are not a native speaker of the language yourself. When it comes to Arabic translations, however, this task may prove to be a bit difficult; due to their religious beliefs, some Arabs will not even partake in the translation if they know it will be used as a tattoo.
If you are interested in getting an Arabic tattoo, keep in mind that Arabic is written from right to left using 18 distinct letter shapes which may vary slightly depending on which letters come before and after. The shapes will change in order to be connected to the letters that surround it. There are also different types of script used in traditional Arabic calligraphy as early as the 7th century: Farsi, Naskh, Kufi, Deewani, Req'aa and Thuluth.
Again, it is important to consult several different sources to ensure your translation is correct. Native speakers or scholars of the language are your best bet. Although the Internet is ripe with translation services, finding one can be difficult when it comes to Arabic because there are not many that specialize in Arabic translations.