ELLIOTT ABRAMS' testimony was in many respects the most revealing and painful yet heard in the Iran-contra hearings. Here was a ranking State Department official showing himself to be an enthusiast so committed to the pursuit of a challenged policy that he had been prepared to set aside considerations -- factuality, openness, the building of trust -- that should be the basic and normal stuff of conducting government business, especially when the policy is hotly contested.

Mr. Abrams presented himself as the scrupulous and unoffending or minimally offending victim of an administration division of labor in which the State Department had only one walled-off part, and perhaps not the principal part, of the president's Nicaragua policy. But to conduct his assigned business and meanwhile keep himself plausibly in the dark about the rest, traces of which were to be seen almost everywhere, was truly a meticulous and demanding labor. Mr. Abrams performed it with a diligence that alternately saddened and enraged those who heard his tale.

Certainly a measure of political vengeance was taken on the essentially unrepentant Mr. Abrams by some of those who questioned him. Congress, after all, is embarrassed to have failed so dismally its duty of oversight. And it recurrently provided the administration with revised rules of the game, which it had to know was being played right up to the edge of what was allowed. The main thrust of the questioning, however, fell elsewhere. ''We cannot advance United States interest if public officials who testify before the Congress resort to legalisms and word games, claim ignorance about things they either know about or should know about and at critical points tell the Congress things that are not true,'' said chairman Lee Hamilton. To us, this summary of congressional sentiment was neither partisan nor narrowly protective of congressional prerogative but legitimate and expressive of the core requirement of democratic policy making.

Mr. Abrams at once received a ringing endorsement from the secretary of state, who, from what is known, fully supported his work through the whole Boland Amendment passage. But Congress has made it clear it cannot accept the kind of relationship with the State Department and the administration as a whole that emerged from Mr. Abrams' reluctant testimony.