For the personal ending am of the 1st person singular (in the Aorist) ma -- anekālśitsarvasya [[1.1.55]] is substituted in the chandas (Vedas).,
The अम् here is the substitution of मिप्, and not the accusative singular affix. As वर्धी वृत्रम् (for अवधिपम्) Rig I. 165. 8: क्रमीम् वृक्षस्य शाखाम् ॥ The अट् augment is diversely elided 6.4.75. The indicatory श् of मश् shows that the whole of the affix अम् is to be replaced. The substitution of म् for म् is to prevent the change of म् into anusvara as in 8.3.25.,