אדנ-י שפתי תפתח תשי”ב

This Ma’amar said by the Rebbe on his fiftieth birthday deals with the idea of this Possuk which is added at the beginning of the Amida and appears to interrupt the סמיכות גאולה לתפילה. The Gemara explains it using the logic of תפילה אריכתה The Ma’amar explains that תפילה אריכתא means much more than an elongated prayer but a prayer from the level of Aruch (Kesser) that therefore descends very low.