I didn't find much on Justine except census data, and Death cert listing, which does provide the Volume and Cert No. which may provide more details.
Samuel appears to be the son of Henry Middleton Sweat and Lavinia Caroline Patrick. Don't know if you are looking for details on him as well? There are lots of records on family search for Samuel and his siblings. Examples below.
Florida, Deaths, 1877-1939
Citing this Record: "Florida, Deaths, 1877-1939," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/FP3M-RBX : accessed 30 Jul 2014), Justine Sweat in entry for Samuel H. Sweat, 12 Sep 1935; citing Mulberry, Polk, Florida, reference 15392; FHL microfilm 2135812.
Name: Samuel H. Sweat
Death: 12 Sep 1935 Mulberry, Polk, Florida
Male White Married
Age : 69y
Birth Date: 12 Feb 1866 Birthplace: S.C.
Spouse: Justine Sweat
Father: Middliton Sweat Birthplace: S.C.
Occupation: Merchant
Residence Place: Mulberry, Polk, Florida
Cemetery: ... Oaks
Burial Date: 13 Sep 1935
Citing this Record: "Florida, Death Index, 1877-1998," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/VV95-GR8 : accessed 30 Jul 2014), Justine Sweat, 1941; from "Florida Death Index, 1877-1998," index, Ancestry.com (www.ancestry.com : 2004); citing vol. 940, certificate number 7165, Florida Department of Health, Office of Vital Records, Jacksonville.
Name: Justine Sweat
Death : 1941 Polk, Florida
Female White
Certificate Number: 7165 Volume Number: 940
U S Census, 1880 Dorchester, Colleton, South Carolina
Citing this Record: "United States Census, 1880," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M6S4-QJY), S A Sweat in household of H M Sweat, Dorchester, Colleton, South Carolina, United States; citing sheet 378B, NARA microfilm publication T9.
H M Sweat Self M 52 SC
L C Sweat Wife F 46 SC
S A Sweat Son M 14 SC
M J Sweat Dau F 9 SC
D E Sweat Son M 3 SC
C H Sweat Son M 7 SC
J F Sweat Son M 11 SC
A W Sweat Son M 17 SCs
U S Census, 1870 Colleton, South Carolina
Citing this Record: "United States Census, 1870," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M8RD-8R5 : accessed 30 Jul 2014), Samuel Swett in household of Ned Swett, South Carolina, United States; citing p. 93, family 729, NARA microfilm publication M593, FHL microfilm 000552991.
Ned Swett M 42 South Carolina
Carline Swett F 40 South Carolina
Philip Swett M 16 South Carolina
Julia Swett F 14 South Carolina
Anna Swett F 12 South Carolina
Catharine Swett F 10 South Carolina
Albert Swett M 6 South Carolina
Samuel Swett M 4 South Carolina
Frank Swett M 2 South Carolina
Henry M Sweet/Lavinia Caroline Patrick below:
https://familysearch.org/search/record/results?count=20&query=%2Bgivenname%3A%22henry%20M%22~%20%2Bsurname%3Asweet~%20%2Bbirth_place%3ASC~%20%2Bbirth_year%3A1830-1835~%20%2Bspouse_givenname%3A%22lavinia%20caroline%22~%20%2Bspouse_surname%3Apatrick~
Lavinia/Caroline Sweet with children:
https://familysearch.org/search/record/results?count=20&query=%2Bgivenname%3A%22lavinia%20caroline%22~%20%2Bsurname%3Asweet~%20%2Bbirth_place%3ASC~%20%2Bbirth_year%3A1830-1835~%20%2Bspouse_givenname%3A%22henry%20ned%22~%20%2Bspouse_surname%3Asweet~%20%2Bfather_surname%3Apatrick~
User submitted pedigrees – are not always accurate and should be confirmed with sources. Sam/Henry/etc. below:
https://familysearch.org/pal:/MM9.2.1/S54T-84Q