Behold, God is my salvation; I will trust, and not be afraid: for the LORD JEHOVAH is my strength and my song; he also is become my salvation. The Lord Jehovah - The word יה Yah read here is probably a mistake; and arose originally from the custom of the Jewish scribes, who, when they found a line too short for the word, wrote as many letters as filled it, and then began the next line with the whole word. In writing the word יהוה Jehovah, the line might terminate with יה Yah, the two first letters; and then at the beginning of the next line the whole word יהוה Yehovah would be written. This might give rise to יה יהוה Yah Yehovah. The Yah is wanting here in two of Dr. Kennicott's MSS., in one ancient MS. of my own, and in the Septuagint, Vulgate, Syriac, and Arabic. See Houbigant and De Rossi.
My song - The pronoun is here necessary; and it is added by the Septuagint, Vulgate, and Syriac, who read זמרתי zimrathi, as it is in a MS. Two MSS. omit יה Yah, see Houbigant, not. in loc. Another MS. has it in one word, זמרתיה zimrathyah. Seven others omit יהוה Yehovah. See Exodus 15:2, with Var. Lect. Kennicott.