You can find your ancestor's birth record here:
Peter Richard Maurer
Born in Istein on September 20, 1847 to Peter Maurer, a shoemaker, and Anna Maria Geither ?.
And his parents marriage record:
Peter Meinrad ? Maurer & Anna Maria Geether ?
The son of Alois Maurer (deceased) and Solomea ? Müller (alive), born April 8, 1815 ? in Istein, got married to the daughter of Johann Geether ? and Maria ...ger ?, born May 22, 1819 in Schlechtenhaus [Schlächtenhaus] on April 23, 1846.
Peter Meinrad Maurer
Born in Istein on April 8, 1815 to Aloys Maurer, a vintner or vineyard worker ("Rebmann"), and Salome née Müller.
Anna Maria Grather ?
Born in Weitenau on May 22, 1819 to Johannes Grather ? and Maria Gselliger ?.
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Apologies for the many question marks and different spellings. Have a go yourself. Here's a genealogy page on Istein (in German):
Istein
"Digitalisate" takes you to scans of the birth, marriage, and death records.
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One more edit. Indexed family registers (Ortsfamilienbuch, or OFB for short) are available for Weitenau and Wieslet, which are close by Schlächtenau:
OFB
Click "Gesamtliste der Familiennamen" to enter. Then look for Grether and Geselliger.
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