בא על החתום

From בא (“to come”) + על (“on, upon”) + ה־ (“the”) + חתום (“signed, sealed”).

• (Modern Israeli Hebrew) IPA^(key): /ˌba al haχaˈtum/
• (Modern Israeli Hebrew, very formal) IPA^(key): /ˌba al heχaˈtum/
• (Mizrahi Hebrew) IPA^(key): /ˌba ʕal haħaˈtum/

בָּא עַל הֶחָתוּם • (ba al hekhatúm) (pa'al construction)

1. (formal) To undersign.

• This phrase is considered flowery, and used almost exclusively as the final clause of contracts and formal agreements to introduce the signatories.
• The he of החתום is vocalized with segol according to traditional norms, but is usually pronounced "ha-", like the normal pronunciation of the definite article. The extra formal pronunciation "... hekhatúm" is falling out of use.

See conjugation at בָּא (ba).