矢や先さきに

adverb

just when; just as; at the very moment when; on the point of

Used when something happens right at the moment someone is about to do something, often with a nuance of interruption or coincidence. Typically follows a verb in the volitional or dictionary form + とする/とした.

• 出でかけようとした矢や先さきに、電でん話わが鳴なった。

  Just as I was about to go out, the phone rang.

• 彼かれに話はなしかけようとした矢や先さきに、彼かれは立たち去さった。

  Just when I was about to speak to him, he left.