Note: this is just a suggestion as I am no expert and there is a wide variety shown within many species of sparrow.
However, according to the couple of guides I looked at and from my memory of those I've seen in the field, Savannah Sparrow has a pinkish hue to its bill. And while the upper mandible may be grey, the lower seems to always have a pink cast. I would also shy away from Savannah Sparrow because I feel that the crest is too reddish and is more in line with Song Sparrow.
I tend to think of Lincoln's Sparrow as having a much more grey face. Then again, I have long ago learned that one can't always trust that the colours in a photograph are actually accurate. But I would (somewhat tentatively) submit that the bird is a Song Sparrow.
Say, he asked, using his standard line for Empid flycatchers, did you hear it sing?