Lady Macbeth strengthens Macbeth's resolve to kill Duncan in Act 1, scene 7, when he's told her that "We will proceed no further in this business" (1.7.34). She does so by insulting his masculinity and implying that he will not be a real man if he does not go forward with the murder. She asks him, "Was the hope drunk / Wherein you dressed yourself? Hath it slept since? / And wakes it now, to look so green and pale / At what it did so freely? From this time / Such I account thy love" (1.7.39-43). She asks if Macbeth's earlier hope was simply drunk and how it can wake now and seem too be afraid of what it would have dared before. She says that, from now on, she'll think the same way about his love: that both he and it lack commitment and resolve. Further, she implies that he'll have to think of himself as a "coward" forever if he will not pursue the crown now (1.7.47). Lady Macbeth says that when he dared to do it, "then [he was] a man," and that he would be "more the man" now if he will (1.7.56, 1.7.58). She even claims that she would rather kill her own baby, had she promised him she would do so, than to go back on her word to him. She wounds his pride over and over, tearing down his manhood and even insisting that she is stronger and more committed than he.
Further, Lady Macbeth argues that no one will be able to suspect them when "[they] shall make [their] griefs and clamor roar / Upon his death" (1.7.90-91). She plans to get Duncan's grooms so drunk that they won't be able to remember anything about the night before, so she and Macbeth can basically do whatever they want to the sleeping king. Then, the couple will seem to grieve and mourn so much that no one will think they had anything to do with the murder. After insisting that Macbeth will not be a man unless he takes the throne by force, she assures him that he is safe to do so because no one will suspect them.