The single most important belief in Judaism is the belief in monotheism, the oneness of God. This key principle is attested to in this fundamental verse, known as the Shema, which is recited twice each day by Jews. In the unique system of gematriya, in which every Hebrew letter is assigned a numerical value, the word echad (אחד), which means ‘one’ and is translated here as ‘alone,’ adds up to 13: א equals 1, ח equals 8, and ד equals 4. Interestingly, 13 is also the numerical value of the word ahava (אהבה), ‘love,’ as א equals 1, ה equals 5, ב equals 2, and ה equals 5. The hidden message of this gematriya is that the greatest love a person can feel is the love of the one and only God, whose very essence is love.
Source: Israel in the News
