What is the ruling of Islamic law on uttering a letter from the letters of a vow without uttering the entire word of the vow or specifying what is vowed, and is expiation obligatory when typing the word "نذر" (vow) on an internet browser without the intention of vowing, then typing "نذر اللجاج" (vow of obstinacy/anger) next to it to avoid expiation?

Uttering a letter or writing the word "nadhr" (vow) does not constitute a vow, especially if the object of the vow is not mentioned, because a vow is only binding when expressed in a formula that indicates commitment to an act of devotion that is not obligatory. Therefore, no expiation is required for what was uttered or written, due to the absence of a formula of commitment and mention of the object of the vow. A vow is a commitment made by speech, not merely by intention, and it requires an utterance that conveys commitment.