I.
When my love swears that she is made of truth,
I do believe her, though I know she lies,
That she might think me some untutor'd youth,
Unskilful in the world's false forgeries,
Thus vainly thinking that she thinks me young,
Although I know my years be past the best,
I smiling credit her false-speaking tongue,
Outfacing faults in love with love's ill rest.
But wherefore says my love that she is young?
And wherefore say not I that I am old?
O, love's best habit is a soothing tongue,
And age, in love, loves not to have years told.
Therefore, I'll lie with love, and love with me,
Since that our faults in love thus smother'd be.
Compare to  Sonnet 138 ’s line 11: 
 But wherefore says she not she is unjust?
The Passionate Pilgrim: 1