(There is no verse va'Yechaser!) Rashi (103a) - I heard that outside it is written 'va'Ye'aser. Radak (Shmuel II, 15:21) ? when there were discrepancies among texts, and Chachamim could not decide, sometimes they wrote one inside and one outside. Ramah (102b) - it is written va'Yechaser, and we pronounce it 'va'Ye'aser. Because he repented covertly, Hashem hid His acceptance of it from Midas ha'Din. It should say only "va'Yishma Techinaso." Va'Ye'aser is extra, to expound like Machteres. Matanos Kehunah (on Devarim Rabah 2:20) ? we expound va'Ye'aser like va'Yechater, for Ayin and Ches are interchangeable. Chidushei Agados Maharal (103a) ? the text should say, why does it say "va'Ye'aser Lo va'Yishma Techinaso"? It should say va'Yishma va'Ye'aser Lo, for He heard before he accepted his prayer! Rather, this teaches that first Hashem dug [an opening for his Tefilah], and afterwards his Tefilah entered. Or, it says va'Ye'aser first, for once He dug an opening, it is called that He accepted it, for He dug it in order that it will be heard!